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OF THE
SOUTH AFRICAN
PHILOSOPHICAL SOCIETY.
fy OWE WV An Er.
1886—i889.
2ES2O CAPE TOWN : PRINTED FOR THE SOCIETY BY MURRAY & St. LEGER. 1893, _
> Fi —
COUNCIL
OF THE
Soil Alvican Philosophigul Sooiety
FOR 1886—1887.
H. Bolus, F.L.S., President.
Hon. C. A. Smith, M.A., Treasurer. W. H. Finlay, M.A., F.R.A.S., General Secretary, J. H. Meiring Beck, M.D.
A. A. Bodkin, M.A.
David Gill, LL.D., F.R.S., F.R.A.S. F. Guthrie, LL.B.
P. MacOwan, B.A., F.L.S.
Hon. J. X. Merriman, M.L.A.
L. Péringuey, F.Z.S.
Ro Gumen, RS. hls. EZ.5-
FoR 1887—18x8,
W. dH. Finlay, M.A., F.R.A.S., President. Hon. C. A. Smith, M.A., Treasurer. David Gill, LL.D., F.R.S., F.R.A.S., General Secretary. H. Meiring Beck, M.D.
. Bolus, F.L.S.
Guthrie, LL.B.
MacOwan, B.A., F.L.S.
Marloth, Ph. D., M.A.
X. Merriman, M.L.A.
Péringuey, F.Z.S.
2 Erimen, DOR; Sse, US.. Ee ZS.
RS wt
FOR geeria ceea
W. H. Finlay, M.A., F. R. A. Ss : President.
Hon. C. A. Smith, M. A. “Tivasuier. David Gill, LL.D. E:B.8 a R. ‘: Si General Secretary.
J. H. Meiring Beck? 3 M: ine
H. Bolus, F.L.S.
F. Guthrie, LL.B.
R. Marloth, Ph.D., M.A.
Hon. J. X. Merriman.
P. MacOwan, B.A., F.L.S.
L. Péringuey, F.Z.S.
R. Trimen, F.R.S. F.L.S., F.Z.S.
@ @ enter ES.
Minutes of Proceedings, 1886-87
Report of the Council, 1887, July 31
Minutes of Proceedings, 1887-88
Report of the Council, 1888, July 31
President’s Address, 1888, August 29
Minutes of Proceedings, 1888-89
Report of the Council, 1889, July 31
President’s Address :
List of Members, 1889, July | at a: :
Mr. A. é Howard, The Winter Storms of South Africa, Illustrating the value of Cape Point as a Warning Station a ae a “he sae :
Mr. J. E. Macnellan, C.E., On Van Wyk’s Vley Reservoir
Mr. R. Marloth, Ph.D., M.A., The “ Naras,” Acan- thosicyos Horrida, Hook.
Mr. W. H. Finlay, M.A., F.R.A.S., The Orbit of Comet 1886 (Finlay). ae
Mr. A. G. Howard, The Storms of South Africa sels
Mr. R. Marloth, Ph.D., M.A., On the Adulteration of Brandy
Mr. W. H. Finlay, M.A., F.R.A.S., Approximate Tide- Constants for Table Bay-and Algoa Bay
Mr. A. G. Howard, The Barometer: Its Reduction to Sea Level
Mr. R. Marloth, Ph.D., M.A., The Acacias of Southern Africa
Professor Guthrie, LL.B., On the Subjective Causes of Evolution as illustrated by the Geographical Distribution of Plants
Mr. R. Trimen, F.R.S., Note on Teeth of the Ziphioid W hale =a a Sr ip nee
Mr. C. Ray Woods, On some Photographs of Lightning Flashes Bp a py 5% Bs
Mr. C. Ray Woods, Photographs of Lightning F iasucx taken September 18, 1888 ... oS zis
Mr. W. Hammond Tooke, The Star Lore of the South African Natives
Mr. R. H. Hammersley-Heenan, M. Inst. C.E., A Short Account of the Attacks of the Teredo Navalis and Cheiura Terebrans upon Greenheart and Sneezewood
Prof. Guthrie LL.B., Sea Levels in South Africa from Barometric Observations
Mr. H. Carrington Wilmer, The Relation of the Sand Dune Formation on the S.W. Coast of Africa to the Local Wind Currents
PAGE
bo ideo) Or
326
ERRATA.
VOLUME V.- PART Ii.
Page 229, in title, for ACANTHOSIOYOS read ACANTHOSICYOS. 229, line 7, for Acanthosioyos read Acanthosicyos.
230, line 18, for rolaquint read coloquint.
267, line 27, fon rafira read caffra.
a3 6 » for spinoza read spinosa.
» line 28, for ferax read feroz.
268, line 5, for glameroles read glomerules.
?
ms ,, line 16, for stolanifera read stolonifera.
= 5, line 21, for detaneus read detinens.
- ,, line 26, for detineus read detinens.
» 269, line 31, for haematosylon read haematoxylon. y» 9» line 36, for Oaffra read Caffra.
271, line 3, for eriolaba read ertoloba. 272, line 21, for Fir read The.
273, line 31, for destineus read detinens.
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MINUTES OF PROCEEDINGS.
Ordinary Monthly Meeting. TuEspay, Auaust 24, 1886.
Ven. ARCHDEACON LicHTFOOT, B.D., IN THE CHAIR.
The receipt was announced of a pamphlet by Dr. Emil Cohen {corresponding member of the Society) entitled “‘ Ueber die von den EHingeborenen Siid-Afrikas verwendeten Producte des Mineralreichs ” -and the thanks of the Society were voted to the donor.
An extract was read from a letter from the Rev. G. H. R. Fisk respecting the tortoises he had sent to England. Two of them were found to be new to science. |
Mr. Péringuey said he had found a new tortoise in Namaqualand, -and Dr. Marloth had sent him some from Damaraland of which four were undoubtedly new. cena
Dr. Gibbon’s list of South African Mollusca was presented to the ‘Society. ee
Mr. Finlay announced his discovery of Winnecke’s periodical Comet
on August 19. _ Dr. Shaw exhtbited a petrified branch picked up at Hout’s Bay, _and afterwards read his paper on the ‘Sand Glaciers in S. Africa.” He prefaced it by an account of the sand-dunes on the East Coast of England and West of Scotland.
Mr. J. C. Silberbauer described the petrification of a large forest in California, 1,000 feet above sea level.
Mr. Péringuey said that some sand-glacier formation was to be found at Kalk Bay.
Mr. Sawerthal had seen specimens, like the one exhibited by Dr Shaw, in the Drakensberg.
The thanks of the Society were voted to Dr. Shaw.
Mr. Woods gave an account of the photographic observations to ‘be made at the Royal Observatorv on the occasion of the Eclipse of
the Sun on August 29. B
it Minutes of Proceedings. Ordinary Monthly Meeting. TuEspaY, SEPTEMBER 28, 1886.
Mer. F. F. RuTHERFOORD, IN THE CHAIR.
Mr. Advocate Innes and Mr. T. J. Anderson were duly elected ©rdinary members of the Society.
Dr. Gill reported the discovery, by Mr. Finlay, of a Comet on Sunday, Sept. 26, 1886.
Mr. Péringuey reported an important discovery he had made: regarding the habits of the Phylloxera Vastatrix. He had found that. when the weather became cold the false female assumed a leaden hue- and became motionless, but revived on being subjected to a high temperature, but did not lay. This was very important considering: the difficulty that had been experienced in obtaining a sufficient supply. of Bisulphide of Carbon, inasmuch as it shewed that there could have been no spread of the disease during the winter months. He had now a sufficient quantity of Bisulphide of Carbon to commence the spring: eampaign.
Mr. A. G. Howard then read a paper on “ The Value of Cape Point. as a Warning Station for Meteorological Changes.”
Dr. Gill, Dr. Marloth, and the Rev. G. H.R. Fisk made some- remarks on the subject, and the meeting closed with the usual votes- of thanks. |
Ordinary Monthly Meeting. WEDNESDAY, OcTOBER 27, 1886.
Mr. H. Bots, F.L.S., PRESIDENT, IN THE CHAIR.
Mr. Advocate Leonard, Q.C., Mr. Advocate P. Molteno, Mr. L.- Michell, and Capt. Hewat were duly elected ordinary members of the Society.
The Secretary read Mr. McNellan’s paper on “ Van Wyk’s Vlei Reservoir.”
The Rev. G. Stegmann asked whether there was likely to be any danger of the dam silting up. He strongly advocated the making™ of similar works in the district of Oudtshoorn.
Mr. Merriman was glad to believe the reservoir was a complete success. It had been made at comparatively little cost, holding
oof
Minutes of Proceedings. | ik
35,000 million gallons and costing £20,000. The Cape Irrigation Act had been copied in Victoria with great success, but had failed here from want of combination among the people.
Prof. MacOwan referred to the reports that had been prevalent that the soil at Van Wyk’s Vlei was so brack that nothing would - grow there, and said that this was far from being the case, and that there was no necessity for planting salt bushes, &c.
Mr. J. C. Silberbauer referred to the dreadful drought that had prevailed in the district about Van Wyk’s Vlei for the last four years. He had been informed that the Beaufort Dam was being rapidly silted up.
Mr. Bolus was of opinion that the question of silting up was one of the most important to be considered in the making of dams. He thought similar work should be carried out near populous centres e.g., on the Sunday’s, the Vaal, and the Fish Rivers.
Mr. Merriman said that there was a special machine which was very efficacious in clearing out silt.
Dr. Marloth then read a paper on “ Nara,” a plant which furnishes food for the natives about the neighbourbood of Walfisch Bay.
Mr. Bolus said many efforts had. been made in Europe to cultivate this plant—at Kew amongst other places. In each case the seeds. germinated and the plant grew two or three inches and then died.
Dr. Marloth replied to.a number of questions from various members, and the meeting closed with votes of thanks to Dr. Marloth and Mr. MeNellan for their very interesting papers. -
Ordinary Monthly Meeting. WEDNESDAY, NOVEMBER 24, 1886.
Mr. H. Bouus, F.L.S., PREsIDENT, IN THE CHarR.
Mr. Péringuey exhibited a remarkable instance of mimicry im animals—a crab covered with seaweed—which he had received from Colonel Bowker. The sea-weed was trimmed in such a manner as to afford a hiding-place for the crab while he was waiting for his prey.
Dr. Gill then gave an account of the measurement of a base-line im the neighbourhood of Port Elizabeth by the Trigonometrical Survey: party, prefacing his account by an explanation of the means taken to
obtain a complete survey of the Colony. B2
iv Minutes of Proceedings.
Mr. Finlay read a short note on the Orbit of the Comet discovered by him on September 26, 1886.
Dr. Gill said the discovery of this Comet was a very important discovery, and one that would excite much interest in astronomical
eircles.
Ordinary Monthly Meeting.
WEDNESDAY, JANUARY 26, 1887.
Mr. H. Botus, F.L.S., PRESIDENT, 1N THE CHAIR.
The Rev. B. P. Marchand, B.A., and Mr, James Easton were duly elected ordinary members of the Society. The following donations of books were announced and the thanks of the Society voted to the donors : Annual Report of the Department of Mines, New South Wales, 1885. Bulletin de la Société Impériale des Naturalistes de Moscou, 1386, Not Annalen des K. K. Naturhistorischen Hofmuseums, Band I., No. 2. Boletin de la Academia Nacional de Ciencias en Cordoba, Vol. VIIL., part 4. Journal of the Cincinnati Society of Natural History, Vol. IX., parts 2 and 3. Colonial and Indian Exhibition, 1886—Descriptive Catalogue of a Collection of Economic Minerals of Canada, by the Geological Corps. List of Donations to the Bodleian Library in 1885. Report of the Trustees of the Australian Museum for 1885.
Prof. Guthrie exhibited a specimen of quartz from the Cape Flats.
The Rev. G. H. R. Fisk exhibited a snake from Touws River which was new to him and to Mr. Irimen.
Mr. Péringuey thought it a very young specimen, and that it might be an Elaps.
Prof. MacOwan sent for exhibition specimens received from Dr. Duminy of the bark of trees which was said to be an infallible anti- dote for the poison of snake-bite.
Mr. Péringuey described some experiments he had made on the potency of snake-poison. He did not believe that anyone had ever recovered from the bite of a colubrine snake.
Minutes of Proceedings. Vv
Mr. Bolus suggested that Mr. Péringuey and Dr. Marloth should make some experiments on this alleged antidote and these gentlemen expressed their willingness to do so.
Mr. Finlay gave a short account of the large Comet which was visible in the South-West. He stated that its path showed it was a member of a system of comets which pass very close to the sun, a system which includes the Comets 1848 I., 1880 I., and 1882 II.
Ordinary Monthly Meeting.
Wepnespay, Marcu 21, 1887.
Mr. H. Botus, F.L.S., PRESIDENT, IN THE CHAIR.
The following presents were announced and the thanks of the Society voted to the donors :
Annuario del Observatorio Astronomico Nacional de Tacubaya (Mexico) 1887. :
Bulletin de la Société Impériale des Rauitaliside de Moscou, 1886, No. 3.
Journal and Proceedings of the Royal Society of New South Wales, Vol. XIX, 1885. :
Notes on Insects apparently of the genus Margarodes, Lansd. Guilding, by R. Trimen, F.R.S.
Mr. Trimen exhibited some ground pearls from ants’ nests. Similar shells from the West Indies sixty years ago were sent to the British Museum. Mr. Trimen had secured three specimens of the insect - (coccus), and it was peculiar as having no mouth. Very little is known about the insect at present. |
Mr. Ponder exhibited some microscopic photographs taken by himself.
Mr. Bolus then read his ‘“‘ Notes, Chiefly Botanical, on the country between Delagoa Bay and Barberton.”
Dr. Marloth said that several of the plants mentioned by Mr. Bolus had been found by him in Damaraland.
An interesting discussion followed, in which Messrs. Péringuey, Trimen, Merriman, and Dr. Murray took part.
The meeting closed with an unanimous vote of thanks to Mr. Bolus for his paper.
Vi [Minutes of Proceedings.
Ordinary Monthly Meeting. WepNEsDAY, Marcy 30, 1887.
Mr. H. Botvs, F.L.S., PRESIDENT, IN THE CHAIR.
The following presents were announced and the thanks of the Society voted to the donors : From Smithsonian Institution : Smithsonian Report, 1884, 2 vols. Proceedings of the American Philosophical Society, Nos. 96-123. Laws and Regulations of the American Philosophical Society. Register of Papers published in the Transactions and Pro- ceedings of the American Philosophical Society. List of Members of the American Philosophical Society from its formation to March 15, 1880. List of Surviving Members of the American Philosophical Society on March 5, 1886. Journal of the Cincinnati Society of Natural History, Vol. VIIL., Nos. 1-4, Vol. [X., No. 1.
Bulletin of the California Academy of Sciences, Vol. II., No. 5.
The Rev. G. H. R. Fisk exhibited a snake caught near the Black River—probably a young specimen of the “ Cross Snake.”
He also read a few notes on the effect of the sting of the scorpion, with especial reference to the alleged death of a girl at Hopefield. He believed that the girl had probably been bitten by some other animal, e.g., a horned adder, and cited several instances of people who had been stung by scorpions without serious result.
Mr. Trimen said that the only other animal besides a snake that could have inflicted the double bite in this case was one of the large spiders. |
Ordinary Monthly Meeting. WerpNEspDAy, May 4, 1887.
Mr. H. Bouus, F.L.S., PRESIDENT, IN THE CHAIR.
The following donations were announced and the thanks of the Society voted to the donors. Jahrbucher der -K.K. Central-Anstalt fur Meteorologie and Erdmagnetismus, 1885.
Minutes of Proceedings. vii
Journal of the Cincinnati Society of Natural History, Vol. IX., No. 4.
Memoirs of the Literature College, Imperial University of Japan, No. 1.
Mr. Péringuey exhibited a snake, Homolosoma lutrix, with two heads, which was alive when it reached him, and was able to put out . two tongues.
Mr. Howard read a paper on “ The Storms of South Africa.”
The author had found that none of the usual theories proposed would suit the facts as observed at the Cape, and had endeavoured to develope a theory from the results of the 8 a.m. simultaneous meteorological observations. |
The Secretary read Dr. Bachmann’s letter on the supposed fatal effects of a scorpion’s bite.
Mr. Fisk said that all authorities who had studied the subject of scorpions had never discovered any other poison than that connected - with the sting in the tail.
Mr. Trimen was of opinion that the evidence in the two cases was very weak : it did not require much knowledge of Zoology to know that the nippers could not be used for inflicting a venomous wound. Mr. Péringuey said that he had quite recently examined a scorpion ~with great care, but could find no aperture in the nippers.
Mr. Péringuey gave an account of his investigations on the development of the Phylloxera vastatrix at the Cape.
Last year the first winged insect was observed at the end of April, ‘this year in January. A most important question was—would the cold at the Cape be sufficient to cause Phylloxera to hibernate? He found that although the mean temperature did not fall to 47° F., yet there was a semi-hibernation at the Cape.
A vote of thanks to Messrs. Howard and Péringuey closed the proceedings.
Ordinary Monthly Meeting. Wepnespay, May 25, 1887.
‘Mr. H. Botuvs, F.L.S., Presipent, IN THE CHAIR.
‘The following donations were announced and the thanks of the Society voted to the donors : Victorian Year Book, 1885-86. Journal of Cincinnati Society of Natural History, Vol. X., 1.
vill Minutes of Proceedings.
Vierzehnter Bericht des Museums fir Volkerkunde in Leipzig, 1886.
Mitteilungen des vereins fir Erdkunde zu Leipzig, 1883, pts. I, 2, 1884, 1885.
The Rev. G. H. R. Fisk exhibited a snake from Namaqualand (coronella cana), of a different colour from the ordinary ones ; it was salmon-coloured underneath. He also drew attention to some remarks that had appeared in “ Nature” during the present year, that the poison of a snake had no effect upon another snake of the same species, and quoted a case that had come under his personal observa- tion, in which one horned snake (vipera cornuta) had bitten another of the same species, with the result that the attacking snake died, apparently from exhaustion, whilst the one bitten remained unaffected. -
Dr. Shaw exhibited an otolith of a whale found on Robben Island.
Prof. MacOwan exhibited an African variety of alectoria jubara found near Smithfield, O.F.S.
Dr. Beck then read his paper on ‘‘ Physiology Teaching in Schools.”
An exceedingly interesting discussien ensued in which Messrs. - Merriman, Fisk, MacOwan, Bolus, and Sir J. H. de Villiers took part. - All the speakers with the exception of Mr. Merriman agreed with Dr. Beck as to the advisability of introducing the study of Elementary Physiology into schools. Mr. Merriman was of opinion that more harm than good would be done by teaching young lads a smattering of this subject at an age when they ought to be studying History and- Geography.
A vote of thanks to Dr. Beek closed the proceedings.
Ordinary Monthly Meeting.
WEDNESDAY, JUNE 29, 1887. Mr. H. Botus, F.L.S., PREsiprnt, 1n THE CHAIR.
Dr. Marloth read a paper on “ The Adulteration of Brandy,” and’ in connection with it he exhibited a number of specimens of brandies containing various amounts of fusel oil.
An interesting discussion followed the reading of the paper.
Mr, Easton desired to know whether the brandy containing fusel oil would not fall under the penalties of Act No. 28 of 1883.
Mr. Sivewright enquired whether age would not remove the fusel:
Minutes of Proceedings. ix
oil, and Dr. Marloth explained that this might be the case to a certain limited extent but he had no actual experience of such changes.
Prof. MacOwan gave an account of the brandy distilled by Messrs. Parkes Brothers of Wheatlands in the Graaff-Reinet district. He thought it probable that the new oak casks in which the brandy was put absorbed some of the alcohol of the amyl series, and thus improved its quality.
The Rev. G. H. R. Fisk referred to the connection of the low- class brandies with the prevalence of crime, and thought the Legis- lature should take steps in the direction pointed out by Dr. Marloth.
A vote of thanks was then conveyed to the latter gentleman for his» interesting’ paper.
Ordinary Monthly Meeting. WEDNESDAY, JULY 27, 1887.
Mr. H. Botus, F.L.S., PRESIDENT, IN THE CHAIR.
The following books were announced as having been presented to « the Society and the thanks of the Soziety were voted to the donors : Journal of the Cincinnati Society of Natural History, Vol. X., 2. . Meteorologische Beobachtungen am Met. Obs. der Landwirtschaft- - lichen Akademie bei Moskau. | Bulletin de la Société Impériale des Naturalistes de Moscou, . 1886 No. 4 and 1887 No. 1.
Dr. J. A. Ross was elected an ordinary member of the Society.
Dr. Gill read his lecture on “The Applications of Photography in- Astronomy.” In the course of it he gave an account of the proceed-- ings of the Photographic Conference held at Paris in April last, and- the resolutions passed by the large body of astronomers there assem- bled with reference to the construction of Stellar Charts.
The Hon. C. A. Smith remarked that a wide field for investigation was opened with respect to the photographic magnitudes of stars as compared with telescopic magnitudes ; and that it would be interesting to take a photograph of the Coal-sack with very long exposure.
Dr. Atherstone called attention to the date as being the Jubilee of Telegraphy. Fifty years ago he was present at the Academy of Sciences, Paris, when Daguerre brought forward his discoveries in Photography, and Morse his Telegraphic system.
A vote of thanks to Dr. Gill closed the proceedings.
x Minutes of Proceedings. Annual General Meeting. WepneEspay, August 17, 1387.
Mr. H. Botus, F.L.S., PRESIDENT, IN THE CHAIR.
The reports of the Secretary and Treasurer were read and adopted. The Members present proceeded to the election of President and ‘Council for the ensuing year, with the following result :—
President: Mr. W. H. Finuay, M.A., F.R.A.S.
Members of Council: Mr. J. H. M. Becx, M.B. Mr. H. Botvs, F.L.S. Mr. D. Gitt, LL.D., F.R.S., F.R.A.S. Pror. GutHRik£, LL.B. Mr. R. Martors, M.A., Pu.D. Hon. J. X. Merriman, M.L.A. Pror. MacOwavn, B.A., F.L.S. Mr. L. PErincuey, F.Z.S. Hon. C. A. Smitu, M.A. Mr.R. Trimen, F.R.S., F.L.S., F.Z.S.
Mr. Belus delivered the Presidential address on ‘“‘ The Flora of the “Cape Peninsula.”
REPORT ON THE PROCEEDINGS OF THE SOUTH AFRICAN PHILOSOPHICAL SOCIETY
DurtInG THE YEAR Enpine 1887, Jury 31.
1. Since the last Annual General Meeting eleven Ordinary Meetings ‘have been held. The average number of members present has been fourteen, and of visitors eight, making an average total attendance of ‘twenty-two.
2, At the Ordinary Meetings fourteen papers nave been read in the subjects Geology, Zoology, Botany, Engineering, Astronomy, Geodesy and Meteorology. Notes and shorter communications on a variety of : Subjects have also been brought before the Society 7) Dies accounts of _these will be found in the Notes of Proceedings. ©
3. Thirty-two presents of books have been received during the
-year; Fifty-eight copies of the Transactions of the Society have been distributed to learned Societies in Europe, America and Australia. — |
4. During the year nine Ordinary Members have been clected, and -eight have resigned. The total number of Ordinary Members is
sixty-eight, and of Corresponding Members twenty three.
5. Volume IV. of the Society’s Transactions is ready for press, and «the printing of it will be commenced in a short time.
W. H. FINLAY, General Secretary.
Xil
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MINUTES OF PROCEEDINGS.
Ordinary Monthly Meeting. WEDNESDAY, AuGuUST 31, 1887. “Mr. W. H. Fintay, M.A., F.R.A.S., Presipent, IN THE CHatr.
Mr. J. Andrews and Dr. R. N. Hormazdje (Howard) were duly elected Ordinary Members of the Society. .
The Rev. G. H. R. Fisk read a short note referring to a return by Sir J. Fayrer in which the phrase scorpion-bite occurred, and also a -note from Sir J.F. saying that this was of course a mistake and should be scorpion-sting.
Mr. Fisk exhibited five specimens of Testuwdo Trimeni, the first that had reached him since the tortoise had been named. This species of tortoise was first exhibited and its peculiarities pointed out by Mr. Fisk in May, 1884.
Professor MacOwan explained the method of arranging in trays the specimens in the Government Herbarium. |
Mr. Péringuey read a paper on “The Economy of Insect-Life in reference to the Fertilization of Plants,’ and exhibited a number of specimens of flies with long rostra specially suited for flowers with deep nectaries.
Prof. MacOwan bore testimony to the value of this paper and des- cribed the process of vegetative reproduction of the Disa Grandiflora.
Mr. Finlay read a paper o: ‘‘ Approximate Tide Constants for Table Bay and Algoa Bay,” pointing out that the tables at present in use were 24 minutes in error.
Ordinary Monthly Meeting.
WEDNESDAY, SEPTEMBER 28, 1887. Mr. W. H. Fintay, M.A., F.R.A.S., PRestpENT, IN THE Cyair.
The Rey. H. M. Foot, Hon. J. W. Sauer, and Mr. Advocate H. B. Sauer were duly elected Ordinary Members of the Society.
xiv Minutes of Proceedings.
M. A. G. Howard reada paper on “ The Reduction of Barometer Readings to Sea-level.” The writer had come to the conclusion that the usual formule could not be used for deducing isobars in such 2 country as South Africa, and he had substituted for them reductions which did not depend on the temperatures at the various stations.
Messrs. Gill, Abercrombie Smith and Finlay, while admitting the uncertainties in the ordinary method of deducing the temperature of the air column between two places, were of opinion that Mr. Howard was wrong in neglecting this temperature altogether.
Mr. Murphy, electrician on the Eastern and South African Telegraph Company’s Ship ‘‘ Great Northern,” gave an account of | the methods of testing and repairing sub-marine cables, and exhibited specimens of the different styles of effecting a joint in a severed cable.
A number of questions were asked by the members in connection: with the subject, to which Mr. Murphy replied.
A vote of thanks to Messrs. Howard and Murphy closed the- proceedings.
Ordinary Monthly Meeting.
WEDNESDAY, OCTOBER 26, 1887.
Mr. H. Bouws, F.L.S., Vick-PRESIDENT, IN THE CHAIR.
The following donations were announced and the thanks of the-
Society voted to the donors : Bulletin de la Société d’Ethnographie. Results of Rain and River Observations in N.S, Wales. Notes upon the History of Floods in the River D. Notes upon Floods in Lake George. The Sydney University Calendar for 1887.
Dr. Marloth read his paper, “‘ The Acacias of Southern Africa,” stating that the landscape north of the Orange River received its- peculiar character mainly from the, in parts, almost exclusive growth of the genus of acacias. This fact induced him to devote some: study to the Acacias of Southern Africa. He mentioned that there are two distinct groups of this plant, one of which alone numbered four hundred varieties. The plant is distributed over the continents of Australia, Africa, Asia and America. Twenty-five varieties belong.
Minutes of Proceedings. Xv
to South Africa, six of wuich are found along the eastern coast districts, three in the eastern part of the Transvaal only, one variety reaches the neighbourhood of Cape Town, and the remaining fifteen thrive chiefly in the Kalahari. Excellent specimens of nearly all these varieties were exhibited during the lecture by Dr. Marloth from collections made during his explorations.
The ensuing discussion was carried on by Messrs. Bolusand Péringuey and the Rev. G. W. Stegmann ; the latter stated that the reots of some of the acacias growing in the Oudtshoorn District reached to a depth of 36 feet. He also extended an invitation to botanical members of the Society to visit Oudtshoorn, promising a rich harvest to collectors since, so far as he knew, Oudtshoorn had been neglected by botanists. Prof. MacOwan testified in warm terms to the great value of this most interesting and carefully prepared paper and moved a cordial vote of thanks to Dr. Marloth which was carried by acclamation.
Dr. J. A. Ross then read “Some Notes on Bacteria in Relation: to Public Health.” He explained that although in many cases Bacteria were fatal to human and animal life it was doubtful whether life would be possible without Bacteria. He strongly advocated the: establishment of a laboratory under Government auspices for the purpose of investigating the various scourges which hanapered farming © so much in this country, and recommended that more study should be given to the subject in future. Dr. Ross exhibited several well-~ prepared specimens by means of his fine microscope.
An animated discussion was carried on by Messrs. Bolus, Pér:inguey and Dr. Marloth, and the meeting closed with a unanimous vote of. thanks to Dr. Ross for his interesting paper.
Ordinary Monthly Meeting. WEDNESDAY, NOVEMBER 30, 1887.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESENT, IN THE CHarR.
Miss L. A. Robinson was duly elected an Ordinary Member of the- Society.
The following donation was announced and the thanks of the Society voted to the donor :
Boletin de la Academia N acional de Ciencias en Cordoba. Vol. IX..
eG Minutes of Proceedings.
Mr. Trimen read his notes on “‘ Some Insects Injurious to Vegetation
-on the Island of Ascension.” A collection of several species of these insects, which had been received from the Farm Bailiff at Ascension
-contributed much towards the illustration of Mr. Trimen’s remarks -on them and their natural enemies.
The thanks of the meeting were voted to Mr. Trimen.
The President next read Mr. W. B. Tripp’s papers on the Rainfall 'S. Africa. 1st: ‘‘ Comparisons of Curves of Rainfall with those of Sun- -spot Energy 1842 to 1886.” 2nd: “ Particulars from all Stations from which records of the Rainfall have been obtained for 10 complete years and upwards up to the year 1886.”
The President pointed out that Mr. Tripp’s giving the distances between the Meteorological Stations will probably convince the public -of the necessity of multiplying these stations, particularly between Aliwal North and Pietermaritzburg.
A discussion ensued in which Drs. Ross and Marloth and Prof. -Guthrie took part. The latter remarked that it appeared useless to -connect rainfall with sun-spot energy.
The unanimous thanks of the meeting were accorded to Mr. Tripp.
Ordinary Monthly Meeting. WEDNESDAY, JANUARY 25, 1888.
Mr. RoLtanp TrimeEn, F.R.S., In THE CHAIR.
Mr. Trimen exhibited on behalf of the captor, Mr. C. W. Morrison, of Estcourt, Natal, a perfect example (received on loan through Col. J. H. Bowker) of the extremely rare, and remarkably beautiful Lycenide butterfly, Aphneus Hutchinsonii, Trimen. The species was founded on a single worn example of the male taken at Estcourt by Mr. J. M. Hutchinson in 1886, and described in Trimen’s ‘ South African Butterflies,” Vol. II., p. 148 (1887). The type specimen (presented to the South African Museum by Mr. Hutchinson) was also exhibited by Mr. Trimen, together with four other South African species of the genus Aphneus. The peculiar beauty of A. Hutchinsonii (which is a considerably larger insect than most of its -congeners) consists in the numerous large glittering silvery or pearly spots of the underside, relieved by black rings on an olive- greenish ground. ‘The nearest recorded ally of this butterfly is A. -Orcas (Drury) of Tropical Western Africa.
Minutes of Proceedings. X Vil
Mr. D. C. F. Moodie’s paper on “The Ethnology of the Zulus ” ‘was then read.
Mr. Selous (a visitor) remarked that the accounts of old forts, buildings, &c., given in many books by South African travellers must be received with great caution. He said that stone walls were to he found everywhere in Mashonaland, and he felt sure they had been built by the Mashonas to enclose and protect their kraals. They had pieces let in of a peculiar pattern which was also carved by the Mashonas on their knives.
After some further remarks by Dr. Marloth and Mr. Trimen the thanks of the meeting were voted to Mr. Moodie for his paper.
Ordinary Monthly Meeting. WEDNEspDAY, FEBRUARY 29, 1888.
“Mr. W. H. FIniay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
The following presents were announced and the thanks of the ‘Society voted to the donors :
Journal and Proceedings of the Royal Society of N.S. Wales, Vol. XX, 1886.
Bulletin de la Société Impériale des Naturalistes de Moscou,
PUSS TN ota; |
Prodromus of the Zoology of Victoria. Decade XV.
Smithsonian Report, 1885, Part I.
Transactions of the New York Academy of Sciences, Vol. V., Nos. 7 & 8.
Annals of the New York Academy of Sciences, Vol. III, Nos. Th '&: 12°
Bulletin of the California Academy of Sciences, Vol. II, Nos. Ore 1.
Proceedings of the American Philosophical Society, Nos. 124 & 125.
Annual Report of the Department of Mines, N.S. Wales, 1886.
Geology of the Vegetable Creek Tin-Mining Field, New England
District, N.S. Wales. c
Vili Minutes of Proceedings.
Dr. Marloth exhibited and described a specimen of the so-called Candle-bush.
Mr. Péringuey exhibited a snake commonly called the egg-eater, which was caught at Admiralty House, in the act of swallowing an egg.
Mr. Fisk said that the late Mr. Oakley had one of these snakes in captivity for some time, and he had seen the shell after ejection by the snake: it was a harmless snake, but had the manner and appearance of a venomous one.
Prof. MacOwan called attention to the deaths of three distinguished scientists who had taken considerable interest in S.A. Botany: Dr. Asa Gray, father of American Botany, Dr. Georg Winter of Leipzig, and Dr. Hugo Lojka of Buda-Pesth.
Dr. Asa Gray, the patriarch of American Botany, who had for many years aceepted and studied out botanical specimens from this country, died December, 1887.
Dr. Georg Winter of Leipzig, one of the most indefatigable of modern mycologists, who had been engaged upon a new edition of Rabenhorst’s Fungi of Europe, took much interest in S. African Fungi, . described and figured many of them. He died August 16, 1887, at a comparatively early age.
Dr. Hugo Lojka of Buda-Pesth, Hungaria, a well-known lichen- ologist, had for several years been engaged in the study of Cape Lichens. His death on September 10, 1887, seemed to have stopped further investigation, but fortunately his work is being carried on by Dr.. Stitzenberger of Korstantz, who will probably in the course of the next two years bring out a descriptive catalogue of all known lichens of Africa from the Algerian coast right away to our southern Cape of Good Hope.
The Rev. Professor Foot then read his paper on ‘ Conservation of Energy in its relation to Mind.”
In the discussion which ensued Messrs. Fuller, Gill, Péringuey,. Guthrie and Beck took part, and the thanks of the meeting were voted to Professor Foot for his paper.
Dr. Gill asked that the next meeting should be held at the Royal Observatory, instead of at the usual place, as he would contribute a paper on the application of Electricity to Astronomy, and the necessary experiments could more easily be performed there.
The President gave a short account of the Comet now visible ané of its future path.
Minutes of Proceedings. X1x
Ordinary Monthly Meeting. WrpneEspay, Marcu 28, 1&88.
Mr. W. H. Finuay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
Mr. J. B. Lindley, M.A., LL.B., was balloted for, and duly elected an Ordinary Member of the Society.
Dr. Gill described the various uses to which electricity was put at the Royal Observatory, where the electric light has recently been installed ; and the Members and their friends then proceeded to inspect the dynamo and engine with which the electricity is generated, the accumulators where it is stored, and the astronomical instruments to which it has been applied for illuminating purposes, viz.: Transit Circle, 7in. Equatoriai, Great Indian Theodolite, Zenith Telescope, Photographic Instrument, and the new Heliometer.
Ordinary Monthly Meeting.
WEDNESDAY, APRIL 25, 1888.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESIDENT, IN THE CHaiR.
Professor Guthrie read a paper on “ The Theory of the Distribution of Plants.” .
Dr. Marloth and the President made some remarks upon the paper, to which Prof. Guthrie replied and the meeting closed with a vote. of thanks to Prof, Guthrie for his paper.
Ordinary Monthly Meeting.
WerpneEspay, May 30, 1888. Mr. W. H. Fintray, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
The following presents were announced and the thanks of the Society voted to the donors :— Janrbiicher der K. K. Central-Anstalt fiir Meteorologie und
Erdmagnetismus, 1886, © c2
2.4 Minutes of Proceedings.
Bulletin dela Société Impériale des Naturalistes de Moscou, 1888, No. 1. Report of Committee appointed to examine into the Scientific Value of Volaptik (American Philosophical Society). Boletin de la Academia Nacional de Ciencias en Cordoba, Vol. Xe eat ol. Victorian Year Book, 1886-87.
Professor MacOwan proposed that the Society should purchase the back parts of the incomplete series at present in the Society’s Library. This proposition was referred to the Council.
Mr. Trimen exhibited a series of specimens (received at the Museum from Mr. Edward Lovett, of Croydon near London) illustrating the still extant but almost extinct manufacture of Gun-flints at Brandon in Suffolk. He called attention to an interesting account of the process, contributed to the Society of /intiquaries of Scotland, and published in the “‘ Proceedings” of that Society for 1887.
In the discussion that ensued Dr. Atherstone, Prof. MacOwan and Dr. Marloth took part.
Dr. Gill drew attention to the “ Report of the Committee appointed to examine into the Scientific Value of Volapik,” just received from the American Philosophical Society, and suggested that some member should report to the Society on the paper.
Prof. Foot was requested to give a report on the subject.
The Rev. G. H. R. Fisk exhibited a snake, Dryophide, genus Langaha, species Crista Galli, a wood snake peculiar to Madagascar. He also placed on record some measurements of testudo pardalis.
Mr. W. E. Fry exhibited diagrams of Isobars 1888, May 21—29, shewing the course of the low pressure during the recent storms.
Ordinary Monthly Meeting.
WEDNESDAY, JUNE 27, 1888.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
The following presents were announced and the thanks of the Society voted to the donors :— Prodromus of the Zoology of Victoria, Decades I. to XIV. Uber die Entstehung des Seifengoldes, von E. Cohen. Goldfiihrende Conglomerate in Siid-Afrika, von E. Cohen.
Minutes of Proceedings. XXl
The Rev. G. H. R. Fisk exhibited a tortoise found near Richmond, genus homopus, of which he described the peculiarities—probably new to science.
Mr. T. Stewart read a paper on “The Geology of the Springs in the Cape Peninsula.”
The paper was illustrated hy several diagrams.
Dr. Atherstone thought the botanical conditions affecting rainfall might with advantage be notified.
Mr. Hutcheons asked about the length of time the rain takes to affect the springs. He had noticed an increase of water in springs just before rainfall, apparently due to low pressure of atmosphere.
Mr. Cairncross stated that the main spring takes about three months before it is affected. He hal noticed springs on Breda’s estate were increased just before rainfall.
Mr. Stewart replied to the various questions and the meeting closed with a vote of thanks to him for his interesting paper.
Ordinary Monthly Meeting. |
WEDNESDAY, JULY 25, 1888. Proressor MacOwan, B.A., IN THE CHAIR.
The following presents were announced and the thanks of the Society voted to the donors :—
Journal of the Royal Society of N.S. Wales, Vol. XXI, 1887. Untersuchung eines Nephelinyenit aiis dem mittleren Transvaal, S.A
Mr. T. Stewart then read his paper on “The Geology of the Springs in the Cape Peninsula ” (read at the last meeting).
In the discussion that ensued, Dr. Marloth, Prof. MacOwan and others took part and Mr. Stewart replied to the various questions asked.
The Rev. Prof. Foot then read a paper on “ Volapiik.”
Dr. Gill, Dr. Marloth, and Dr. Atherstone made some remarks to which Prof. Foot replied, and the meeting then closed with the usual votes of thanks.
Xxu Minutes of Proceedings. Annual General Meeting. WEDNESDAY, AuGuST 29, 1888.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
The Reports of the Secretary and ‘Treasurer were read and adopted.
The members present proceeded to the election of a President and Council for the ensuing year, with the following result :
President : W. H. Finuay, M.A., F.R.A.S. Council: D. Giiz, LL.D. F.RS.
P. MacOway, B.A., F.L.S.
F. Guturiz, LL.B.
R. Trimen, F.R.S., F.L.S., F.Z.S.
Hon. J. X. MERRIMAN.
Hon. C. A. Suitu, M.A.
R. Marziota, M.A., Pu.D.
J. H. M. Brecx, M.B.
L. Perineuey, F.L.S,
H. Bouvs, F.L.S.
Mr. Finlay delivered the Presidential Address on “‘ The Progress of Astronomy during the last 12 years.” |
A vote of thanks to Mr. Finlay for his very interesting and instructive address was proposed by Dr. Gill and carried unanimously.
REPORT ON THE PROCEEDINGS OF THE SOUTH AFRICAN PHILOSOPHICAL SOCIETY
DurING THE YEAR ENDING JULY 381, 1888.
1. Since the last Annual General Meeting eleven Ordinary Meet- ings have been held. ‘The average number of members present has been fourteen, and of visitors eleven, making an average total attendance of twenty-five.
2. At the Ordinary Meetings fifteen papers have been read in the subjects Astronomy, Biology, Botany, Economic Science, Ethnology, Geology, Meteorology, Psychology and Zoology. Notes and shorter communications on a variety of subjects have also been brought before the Society ; brief accounts of these will be found in the Notes of Proceedings. Shien Heo
3. Twenty-four presents of books have been received during the year. A list of these will be found in the Proceedings of the Society.
4, During the year seven Ordinary Members have been elected, and seven resigned ; the name of one member has been removed for non-payment of subscription. The total number of Ordinary Members is sixty-seven, and of Corresponding Members twenty- three.
5. Vol. IV. part 1 has been printed and distributed to members. Vol. IV. part 2 is now in the press and will be distributed in a few -weeks. Authority has also been given for the printing, in England, of a Part of the Transactions containing Mr. Bolus’ plates of Cape Orchids, and the accompanying letterpress.
DAVID GILL, General Secretary.
XLV
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ANNUAL ADDRESS TO THE MEMBERS OF THE SOUTH AFRICAN PHILOSOPHICAL SOCIETY,
On THE 29TH AvaustT, 1888,
By tHE Prestpent W. H. Finuay, M.A., F.R.A.S.
THE PROGRESS OF ASTRONOMY DURING THE LAST TEN OR. TWELVE YEARS.
I propose to bring before you this evening a review of the Progress of Astronomy during the last 10 or 12 years, a review at least of some of the chief points in which our knowledge has been advanced, as an account of all of them would be too long for this address. The theory of Astronomy during this period has not attracted so much of the attention of the younger generation at our Universities, their’ attention having been diverted to the newer theory of Electricity with its manifold developments ; there is however a goodly number of advances in theoretical Astronomy to be recorded, but I cannot venture on a detailed account of them to-night.
A large amount of work has been done in connection with the shape and dimensions of the earth. Bessel’s value of the ellipticity,. or ratio of the difference of the axis of the earth’s spheroid to the major axis, waS 34>. It was derived from arcs of the meridian measured in France, Sweden, Russia, India and Peru. From ex-- tensions of these arcs and new ones, measured with more refined. instruments Col. Clarke has shown that Bessel’s value is too small and that 54, 1s nearer the truth. His result has been confirmed by pendulum observatious in India by Col. Herschel, and by the U.S.- Coast Survey in America. But it has been made abundantly manifest in these investigations that no one spheroid or ellipsoid will represent the earth’s shape with exactitude: and that just as there are departures from uniformity on the earth’s surface in the shape of mountains, there are anomalies in astronomical latitudes and longitudes... Notable examples of these have been found in Russia and the island.
Xxvi President’s Address. [Aug. 29,
of Mauritius, and they probably exist to a greater or less amount elsewhere. Obviously then the proper method of procedure is to adopt some standard spheroid or ellipsoid which shall represent as closely as may be the average shape of the earth and to tabulate the deviations from this standard for each particular place. In this “way the inconvenience of altering our tables with every additional are that is measured would be obviated, while every such are would -add its quota to our knowledge of the true shape of the earth. The approximate determination of the latitude of a place is a simple matter, but an accurate determination free from errors in the refraction tables and from instrumental defects is a very different thing. Prof. J.C. Kapteyn, of Groningen, has proposed a method for securing an accurate result which is now being carried out at the Cape Obser- vatory, but the observations are not yet completed. Numerous deter- minations of difference of longitude by telegraphic signal have been made. Thus Europe and America have been connected by four inde- pendent cable operations: S. America and the United States have been connected, and also S. America and Lisbon. During this last operation, which was carried out by officers of the U.S. Navy, an error of 84 seconds of time (equal to about 21 miles) was discovered in the accepted longitude of Lisbon. How such an error in the position of a place like Lisbon couid have remained undiscovered is inconceivable! Australia and New Zealand have been connected with India : India with Aden, the Cape with Aden,and Aden with Greenwich. Besides these cable operations the Transits of Venus in 1874 and 1882, and several Eclipse expeditions have led to -astronomical determinations in out of the way places, so that, although there yet remains plenty of work to be done in connecting intermediate stations, we may say there are few important places on the earth where accurate Greenwich time is not known. With regard to inter- mediate telegraphic connections I will only mention those carried out in S. Africa, as being of more immediate interest to ourselves. The Cape Observatory has naturally been the standard reference point and with it Durban and Newcastle (Natal), Kokstad, Berlin, Umtata, Aberdeen Road, Montagu Road (now Touws River), and Port Elizabeth have been connected. Five of these determinations were made by Major Morris, R.E., in the course of the Trigonometrical Survey of Natal and the Cape Colony. This survey, undertaken by Natal and the Cape Colony at the instigation of Dr. Gill and under his superintendence, has been carried out by Major Morris with the
1888. | President’s Address. XXVli
-most scrupulous accuracy and with an energy that few men could maintain under the difficult circumstances of such a work. It has now been going on for five years: a chain of triangles has been carried from Newcastle through Natal and into the Colony as far as Port Elizabeth, and base lines were measured at Pietermaritzburg and Port Elizabeth. Everything, it must be remembered, in such work depends on the accuracy with which the base (or starting) line is measured, and the exact co-efficients of expansion of the bars used have yet to be determined ; but still, with the preliminary co-efficients adopted, the length of the Port Elizabeth base calculated from the Pietermarit burg base carried through the 50 triangles over a distance of 600 miles differs from the measured length by less than two inches -and small corrections have yet to be applied which will probably diminish this discordance. It will perhaps give a better idea of the accuracy attained if I put it in this way: to reconcile the two bases exactly it is necessary to correct each of the angles of the triangles by 1-10 of a second of are, a quantity which we cannot measure with certainty with instruments of the present day.
Truly, S. Africa should be proud of having accomplished auek a work and I wish it were more generally appreciated at its true value. When completed it will be an important geodetic measurement, second to none in accuracy, and of lasting benefit to the country in supplying -exact reference points for future surveys: we shall then be able to “say with truth that 8. Africa is the best surveyed colony in the world, Considerable progress has been made in our knowledge of the tides
by Mr. Ferrel, Sir W. Thomson and Prof. Darwin. The height of the tide is 1egarded as being the algebraic sum of a number -of tides due to various theoretical causes: by means of harmonic -analysis the constants of these tides are determined from the records -at any port, and then Sir W. Thomson’s tide-predicter enables us from these constants to predict the tides for any year at the particular station with accuracy. Self-recording tide gauges have for several years been at work at Cape Town, Port Elizabeth and East London, and also self-recording anemometers. They were established at the suggestion of Dr. Gill by the Colonial Government, but most unfor- tunately funds for the reduction of the records are not forthcoming.
.
THE MOON.
In the theory of the Moon’s motion there has not been much pro- gress, though important memoirs have appeared dealing with special
XXVlil President's Address. [Aug. 29,.-
points. Hansen’s lunar tables, published in 1860, were an immense ~ advance on all previous tables: they represented the Moon’s motion with great accuracy over the whole range of reliable observation from 1750 to 1864, and they also gave a fair representation of the - somewhat vague accounts of votal eclipses in ancient times. It was — known from Prof. Adams’ researches that Hansen’s value of the secular acceleration of the Moon’s mean motion was nearly double © its theoretical value, but a possible and plausible explanation of this discrepancy was found in the action of the tides on the time of revolution of the earth. But from 1865 to the present time the Moon has been gradually running away from the tables more and more every - year, so much so that in the year 1887 the errors of the tables - amounted to as much as one second of time. Naturally many attempts have been made to discover the cause of this unpleasant disagreement » between theory and observation. Mr. Neville, Director of the Durban Observatory, is at present engaged ona revision of the lunar theory. Sir G. Airy has published a Numerical theory, founded on Delaunay’s > work, which however has not turned out to be all its distinguished author could have wished. Prof. Newcomb, while engaged in pre-- paring accurate places of the Moon for use in the Transit of Venus expedition, detected several small errors in Hansen’s work but was obliged, in order to satisfy the observations discussed, to introduce further empirical corrections. The introduction of such corrections - really amounts to determining the Moon’s mean motion from recent observations only, and there is no reason to hope that they will hold good for more than a few years: in fact evidence is not wanting to- shew that they are beginning to fail already. Mr. Stone has brought forward an explanation, which however has not met with acceptance - among astronomers : nevertheless, on his hypothesis, Hansen’s tables- continue to represent the Moon’s place as well now as. they did formerly. Several other distinguished mathematicians are also at. work on the subject, and it is to be hoped their labours will let more ’ light on this difficult theory ; but at present the Moon fully deserves its title of “ the refractory satellite.”
A most valuable series of observations on lunar heat has been made. by Prof. Langley by means of the bolometer, an instrument of his: own invention. The rationale of this instrument is briefly as follows :- an excessively thin strip of platinum wire is inserted in two arms - of an apparatus which is practically a Wheatstone’s bridge and a- current of electricity is passed through it ; rays from the object. whose~
-1888.] President’s Address. XKix
\
heat we wish to determine are allowed to fall on the wire in one of -the arms and any increase of temperature acting on the platinum wire retards the flow of electricity ; the balance is disturbed and the effect is immediately shewn on a galvanometer inserted in the circuit. With this instrument he found in 1885 that besides the reflected heat from -the Moon’s surface there were distinct traces of radiated heat, and. he came to the conclusion that the temperature of the surface was -about the freezing point. But even this amount of heat implies .some atmosphere on the Moon, and the existence of which has always been negatived by other observations.
THE SUN.
The great question of the Sun’s distance from the earth is still -ansettled, though the uncertainty has been reduced to within narrow limits. First, in the magnitude of the undertaking, came the expedition -for observing the Transits of Venus over the Sun’s dise in 1874 and 1882. For the former one especially almost every civilized nation in the world equipped parties of observers, who were despatched to -all quarters of the globe where the phenomenon could be favourably observed. It was fondly hoped by many that these two transits would settle the question of the Sun’s distance beyond doubt or cavil, but this opinion was not shared by those who had studied the reports of the appearances observed in the transits of 176] and 1769. But still it was expected that with greatly improved instruments and more -experience good results would be obtained ; besides it would have been an unpardonable piece of neglect not to observe these transits, which are only visible to one generation out of three. And good resuits were obtained, better I think in the transit of 1882 than in -that of 1874; but not by any means good enough to settle the -question. In fact the method is theoretically a very powerful one, but the optical appearances presented change so gradually and are -so perplexing under various conditions of definition that it is almost impossible for observers, widely separated.and under different atmos- pheric conditions, to hit upon exactly the same phase for observation. And bere I should like to record my protest against a statement one -often meets with in popular astronomical literature ; it is said that the method is worthless because different computers. have from the same
data deduced such different values for the Sun’s parallax as 8"°57 and 8" 91. It is quite true that from the transit of 1769 Encke did deduce the value 8"57, and on the authority of his discussion the value of
XXX President’s Address. [Aug. 29,.
95 millions of miles was given for years and years as the Sun’s distance ; but in 1868 Stone shewed in the clearest manner possible that Encke had made a complete mistake in interpreting the observations at Otaheite, and that when this mistake was rectified the value given - was 8°91. A somewhat similar mistake was made in the first result published from the British observations of the 1874 transit, and the error was again pointed out by Stone. I venture to say that no astronomer, who has seen the phenomena himself, will question the - accuracy of Stone’s corrections ; and yet these mistakes are constantly — trotted out to prove that the method is worthless. When the time comes round again for the next transits in 2004 and 2012 they will no doubt be observed, but the question of the Sun’s distance will have - been settled long before that. In 1877 a notable attempt to solve - the problem was made by Mr. Gill, at the island of Ascension, by the method known as that of ‘ Diurnal parallaxes.”” The planet Mars at some of itS oppositions approaches the earth comparatively closely, and is then considerably displaced with reference to neighbouring stars, according as the observer on the surface of the earth sees it . in the morning or evening. _ With a heliometer stationed on the island of Ascension Mr. Gill determined the amount of this displacement with a very high degree of accuracy and the value of the solar parallax deduced was 8""78. This value is considerably smaller than what was judged to be the most probable value pointed out by other ~ good methods, but it is certainly entitled to great weight.
The velocity of ight in combination with the value of the constant of aberration supplies us with another method of determining the solar parallax. Recent determinations of the velocity of light have - been made by Cornu, Michelson and Newcomb. Newcomb’s experi- ments were by far the most complete and elaborate, and his result for the velocity of light at the earth’s surface is probably not in error as much as twenty miles a second. A new value of the constant of © aberration was deduced about the same time, 1882, by Nyrén of the - Poulkova Observatory ; and this value combined with Newcomb’s light velocity gives a parallax of 8"°79, which is strikingly confirma- - tory of Mr. Gill’s result. There is one element of doubt, however, in this method ; can we assume that light travels with exactly the same speed at the earth’s surface as it does in interstellar space? We: cannot tell. In 1872 Galle, of Berlin, proposed that some of the minor planets which come moderately near the earth should be pressed into the service, and an attempt was made iin 1873 with the planet -
1888. | President's Address. XXxi
Flora. As proposed by him the method required the co-operation of observatories in the northern and southern hemispheres, and owing to various unfavourable circumstances the observations in the southern observatories were not sufficiently numerous and good. Another attempt was made in 1882 on the planets Victoria and Sappho ; no result has yet been deduced from these observations, but they will certainly give a very fair result. A grand attack on the problem will be made this year and next with the exquisite heliometer which has recently been erected at the Cape, both independently by the method of diurnal parallaxes and also in conjunction with similar instruments in America and Germany, and results of the highest degree of accuracy may be confidently expected. It is perfectly certain that the minor planet method will give the most reliable determination at the present time, but it is almost equally certain that the final value, to be adopted many years hence, will be deduced from the perturba-- tion of the planets Venus and Mars under the action of the earth as pointed out and already approximately done by Leverrier ; for this. method is one that ever increases in accuracy with the lapse of time.
A very important series of experiments has been carried out by Prof. Langley on the esergy of the separate rays constituting the lower part of the solar spectrum. In, previous investigations the spectrum had been formed by refraction through a prism, as no instrument existed of sufficient delicacy to measure the heat of the diffraction spectrum. But in the prismatic spectrum the rays are- much more crowded together at the red end than at the blue, and the- effect of previous investigations was consequently to indicate a. maximum of heat in the infra-red portion of the spectrum. Hence arose the three curves of solar energy which we are accustomed to- find in the text-books, viz., the actinic, light and heat curves, with maximum value at different parts of the spectram. But in the: diffraction spectrum we have a normal arrangement of the rays side by side without any crowding, and Prof. Langley by means of his bolo-- meter was able to measure the heating effect of each portion in detail. He found that the point of maximum heat practically coincided with that of maximum light, 7.e., near the sodium lines in the yellow. We are- thus led to the conclusion that there is no difference of quality in the rays. themseives, but that the various effects produced by them depend on the various capabilities which the bodies they impinge on possess of turning to account the longer or shorter vibrations.
From simultaneous observations at the summit and foot of Mt..
KXxii President’s Address. (Aug. 29,
Whitney, Langley was also enabled to calculate the effect of the earth’s atmosphere in absorbing the different portions of the spectrum, _and he found that the blue end suffered far more than the red. The solar atmosphere has been shown by Vogel and Langley to have a similar effect in stopping the rays of shorter vibration, so that our view of the Sun is as if two plates of red glass were interposed between us, the removal of which might leave the Sun of a bluish colour.
Photographs of the Sun’s disc are taken on every fine day at -Greenwich, Mauritius, and at Dehra Din in India; so that it rarely happens that there are more than two or three days in the year on which we have not a record of the state of the disc and of the size -and shape of the spots on it.
The study of the chromosphere and the solar prominences has been carried on by many observers, among whom the late Director of the Rome Observatory, Tacchini, deserves particular mention. It cannot ‘be said that any striking result has been reached in connection with them, but a sound foundation is being laid for future investigation.
Total Eclipses of the Sun have been regularly and systematically -observed, expeditions being despatched to any part of terra firma where they may be visible, as aé present it is only on these occasions ‘that we can see that wonderful solar appendage—the corona. The appearances presented by the corona are very different in different eclipses, and there is a large amount of evidence to show that it is ‘most developed at times of sun-spot minima.
The Eclipse of 1878 was particularly well observed in North America, in one case at an altitude of 14,100 feet above the sea-level, -and the great advantage of observing at high altitudes was shown by -the fact that the corona was visible for 4™ after totality.
The brighter part of the corona was reduced to a narrow ring of light round the Sun, but remarkable fainter streamers were seen stretching away right and left of the Sun to a distance of ten millions of miles. The axis of the longest ray coincided with the ecliptic. The idea of -a connection between these streamers and the zodiacal light imme- -diately suggested itself, and in fact we should expect the zodiacal light (which is certainly a solar appendage) to present much the same appearances at its lower parts as were seen in this eclipse. I may mention that a very similar appearance was seen by Stone in Nama- qualand in 1874, but the rays were not visible so far from the Sun’s -dise. Next in importance was the eclipse of May 17, 1882, the chief
18838. | President's Address IN
observations of which were made in Egypt. This was a year when sun-spots were numerous and the appearance of the Corona fully supported the connection with them previously enunciated. No zodiacal streamers were seen, and the general aspect was very similar to that of the eclipse in India eleven years earlier. The eclipse of 1883 was observable only from a small island in the South Pacific Ocean but a considerable party of astronomers flocked there to see it ; the Corona was similar to that seen in 1882. Some important results were obtained, and one very suggestive one by Tacchini. He saw in the spectrum of the Corona on a feeble continuous background two of the bright hydro-carbon bands which are found in the spectra of comets ; the observation however requires confirmation. So far as we can say at present the Corona is certainly not a solar atmosphere inasmuch as its pressure does not increase as the sun’s disc is approached ; it may be defined as gaseous matter constantly flowing from and towards the sun or perhaps circulating round it, under the action of a repulsive electrical force and of gravity. It is chiefly composed of hydrogen and the unknown substance giving the green ray 1474, and partly of solid or liquid particles shining with reflected and inherent light, but it must be of inconceivable tenuity since: comets are able to pass through it without suffering any alteration of velocity.
‘The fact that we have only some four or five minutes a year at the most for the study of these phenomena makes it highly desirable that some means of observing them at any time should be discovered.. This has already been done in the case of the prominences, which are now mapped daily, and an attempt has been made with the Corona. From the photo raphs taken in 1878 Dr. Huggins observed that the light in the spectrum is largely confined to violet rays, and he hoped to find by excluding all but these rays that the glare produced by the. atmosphere plus the coronal light might be sufficiently greater than. the glare alone to render the shape of the Corona visible. His first experiments were made in 1882 and gave a fair promise of success ; the impressions on his plates strongly resembled the Corona in general features and in details ; but the haze or dust that was present in the atmosphere after the volcanic explosion in the Sunda Straits in 1883, August, put an end for a time to work in this direction. Further experiments were made by Mr. C, Ray Woods on the Riffel and at the Cape in the following years, but with no better success. The
eclipse of 1886 was anxiously looked forward to as a crucial D
XXXiv President’s Address. [Aug. 29,
test ; if the method was a sound one it ought to be possible to obtain a picture during the partial phase of the eclipse shewing the moon’s contour against the background of the coronal light. No trace of the Moon however was discernible in the photographs taken at the Cape and Grenada ; and for the present at least the method is not practicable. When the effects of the Krakatoa eruption have entirely passed away, it will without doubt be tried again at some elevated station where the coronal light will not suffer so much absorption by the earth’s atmosphere.
Passing now to the other members of the solar system, we may say with certainty that there is no intra-mercurial planet as large as 300 miles in diameter, though it is very probable that there are ‘intra- mercurial asteroids. During the eclipse of 1578 Swift and Watson claimed to have seen two objects where no stars existed and it was generally thought at first that the missing Vulcan had been found ; but on examining their observations it was seen that they could not possibly be brought into harmony, and itis almost certain that they both observed the same two stars in Cancer, the hurry and excitement of the moment leading to errors in the record of their position. An exhaustive search fur any such planets was made during the eclipse of 1883 with negative results, and we can only come to the conclusion that there is no such object of any considerable size.
Our knowledge of Mercury and Venus has not been greatly increased during the last ten years, but an interesting and successful attempt has recently been made to clear up the mystery of the satellite of Venus which was seen on several occasions in the 17th and 18th centuries. It has usually been supposed that the object seen was a false image or ‘ghost ’”’ arising from some internal reflection in the telescope, but this explanation has been felt to be weak, inasmuch as the supposed satellite was seen on several of the occasions by expe- rienced astronomers who would be fully aware of the danger of deception from such a cause. Last year Dr. Stroobant made a careful examination of the positions given for the satellite and found that the majority of them coincided sufficiently closely with the places of stars of about the 5th magnitude to make it reasonably certain that the objects seen were these stars; and he satisfied himself by actual observation that stars of this magnitude could be seen under favourable circumstances by daytime. Thus another astronomical ghost has been laid to rest.
The planet Mars always comes in for a large amount of attention,
1888. ] President’s Address. XXXV
chiefly because more of the details of its surface are visible than is the case with the others. This is due partly to its proximity to the earth, but chiefly to the tenuity of its atmosphere. It must be rare ‘to admit of these details being seen and yet judging from the behaviour of what are supposod to be polar snows or ice, the climate -seems to be unexpectedly mild. How these apparently contradictory facts are to be reconciled I do not know. In 1877 August a memorable -discovery was made by Prof. Asaph Hall with the 26-inch refractor at Washington, viz., that Mars was the possessor of two small moons. And very interesting little bodies these are :—assuming that they reflect the same proportion of the Sun’s light that Mars does, they are -about 6 and 7 miles respectively in diameter, the inner one being the larger. This inner one revolves round its primary in 7®. 29™. at a distance from its surface of only 38,760 miles, and we are here presented with the unique case of a satellite completing its revolution in less than its primary’s day and coming to the meridian twice or even ‘three times in that day. At this same opposition of 1877 Schiaparelli had observed that what had always been called the continents of Mars were really a collection of islands connected by long markings of about ‘60 miles in breadth which have been called “canals.” These were distinctly visible again from 1881 December to 1882 February, but in many cases were seen to be double, z.e. another canal was found ‘parallel to the original one; and this duplication has been verified in 1886 and the present year. ‘Travelling farther from the Sun we come to the group of asteroids which have now become so numerous that they require the whole attention of a separate department at Berlin to follow their movements and guard against their being lost. ‘The last discovered was number 278 I helieve. Naturally the ones recently discovered are on the average fainter than the earlier ones ; they average about 11 or 12 magnitude and are probably not more than 15 miles in diameter. The chief modern discovery about Jupiter is that he is in a stage midway between the Sun and the Earth; he has not cooled down sufficiently to possess a solid crust, and his vast stores of internal heat give rise to agitations which are shewn by the changes observed in ‘his dise. This discovery however does not belong to the period we are considering. In 1878 Pritchett, Director of the Morrison Observatory (U.S.), observed an enormous rosy cloud near the southern equatorial band ; and in 1879 and the two following years the Great Red Spot, as it was called, attracted universal attention. Its cclour had deepened D2
XXXVi President's Address. [ Aug. 29,
to a full brick-red, and the effect was heightened by the presence of an unusually brilliant white equatorial spot. The two spots completed a revolution in different times, the white one taking about 5} minutes longer than the other; and neither preserved a uniform period throughout. In May 1883 the red spot had become almost invisible, - but in December it began to recover and in 1886 presented much the same appearance as in 1882. The only conclusions as to it nature that we can draw from the numerous observations are merely negative ones; it was not an eruption from a Jovian volcano; it was not attached to the surface of the planet ; it was not a portion of a glowing disc seen through a rent in the enveloping vapours ; and it was not _ self-luminous.
Observations of the eclipses of Jupiter’s satellites led Romer to the discovery that light does not travel instantaneously, and the method was employed by Glasenapp in 1874 to obtain a new determination of the velocity of light. But the ordinary observation of the time of disappearance or reappearance of a satellite is an unsatisfactory one, and a much better plan has ‘been proposed and is being carried out by Pickering. By means of a photometer he determines the instant when the satellite has lost half its light, z.e. when it is half submerged in Jupiter’s shadow and finds he can fix this time with great accuracy. These observations when carried out for 12 years will a a very reliable value of the light-equation and of the solar parallax.
Saturn is probably in a still earlier stage of development than Jupiter; his speeific gravity is so low that he would float in water and as the density increases towards the centre it follows that the .surface cannot be solid or liquid; hence we must regard a large proportion of his globe as consisting of heated vapours, kept in con- stant agitation by the process of cooling. An interesting question suggests itself as to whether the wonderful ring has always main- tained the same dimensions and the same distance from the planet. Otto Struve made in 1851 a most careful determination of the dimen- sions of the system and repeated them under very similar circum- stances in 1882. There appeared to bea slight extension in width of the rings both inward and outward, but so slight as hardly to be separated from the possible errors of observation. Some change there certainly has been, for in 1657 Huyghens described the interval between the ring and the planet as somewhat greater than the width of the ring, while at the present time this interval is only about two- thirds the width of the rings.
1888. ] President’s Address. XXXVil
A magnificent drawing of Saturn and his rings has been made by Trouvelot by the aid of the 26-inch refractor at Washington ; and I am fortunate enough to be able to show you a copy of it. The ‘rotation of the planet Uranus has recently presented a most puzzling problem for the consideration of astronomers. As is well _ known, the satellites revolve ina plane nearly at right angles to the -ecliptic and it might naturally be inferred that the axis about which the planet rotates is situated nearly in the plane of the ecliptic. This ‘inference is supported too by observations of a slight bulging of the disc in the plane of the satellites. But in 1884, from January to June, two grayish parallel markings were distinctly seen at Paris and Nice ; and these markings which must be assumed to lie in planes parallel to the planet’s equator were inclined at an angle of 40° to the plane of the satellites’ motion. This fact was also confirmed by observations of a bright spot which indicated a time of revolution of about ten hours. Does Uranus, then, at the present time rotate in a plane differing widely from the plane of rotation at the far distant. time when the satellites were formed? No solution of this difficulty has yet been proposed. me Whether a planet will ever be found beyond Neptune it is of course impossible to say, but it is not at all unlikely that some day one will be found in the course of the search for minor planets. Two attempts have been made to fix the position of such a body from theoretical consideration, one by Forbes in 1880 and the other by Todd about the same time. Prof. Forbes relied on the fact that comets of short ‘period group themselves into families in such a way that when at their furthest distance from the sun they are near the orbit of some one of the major planets ; he found two considerable groups of comets which reach their aphelia at distances of 100 and 300 times the earth’s distance, and he maintained that there was an unseen planet revolving at each of these distances. Prof. Todd followed the method which in the hands of Adams and Leverrier had led to the discovery of Neptune. The perturbations of Neptune have not had time yet to develope sufficiently, but there are certain anomalies in the motion of Uranus or “residual errors,” as they are called, not accounted for by theory on which he based his investigation. It is remarkable that “both he and Prof. Forbes assigned places for the hypothetical planet which agreed well with one another. | I must not pass away from the planets without briefly referring fo the remarkable investigations of Prof. G. H. Darwin on the subject
XXXVill President’s Address. [ Aug. 29,.
of Planetary Evolution. By the most refined mathematical analysis he calculates the effect produced on the motion of two rotating viscous
bodies by the ‘‘ bodily” tides each would produce in the other. The primary effect of a tide raised on such a body is to diminish its velocity of rotation ; the tide acts as a brake since the interior portions are revelving as it were in a collar, and gradually the body thus acted on tends to turn always the same face to the other. In the case of the moon this has already come to pass. And further the tidal wave produced on the earth by the moon reacts on the moon and pulls her
forward ; now a forward pull of this kind means an enlargement of the moon’s crbit so that she is gradually receding from the earth.
Following this line of reasoning we see that in ancient times the moon must have been very much closer to the earth than at present, and - indeed Prof, Darwin traces her history back to a time when she was revolving close to the earth in a period of between two and three hours. In 1881 he published an investigation, following the same principles, into the early history of the whole solar system ; and he found that the earth and moon formed a singular exception to the other members of the system, owing chiefly-to the moon being much larger relatively to its primary than the other satellites and having in consequence a- very much greater tide-producing power. He was led to the con- clusion that the satellites of the other planets had never revolved in
much smaller orbits than they do at present. Solar tidal friction
however played an important part in determining whether a planet- was to have moons or not, if we accept the view that satellites were produced by the disruption of a too-rapidly rotating primary, as by
checking the velocity of rotation it checked the tendency to disruption.
Hence we see that Mercury and Venus, where the solar influence is
strong, were unable to rotate with sufficient speed to produce satellites . and the earth narrowly escaped the same fate ; while the outer planets,. where the influence of the brake is weak, are well provided with moons..
COMETS.
No great stride has been made in our knowledge of these bodies in spite of the large number of brilliant ones we have been favoured with, but several advances of considerable importance have been secured. There seems to be little doubt that the heads of comets. are aggregations of small particles, the interstices being filled with gaseous vapours, and that the tails are due to electrical repulsion.
1888. | President's Address. XXxXIix
between the sun and these vapours. Bredichin’s division of the tails into three types corresponding to hydrogen, hydro-carbons, and metallic vapour respectively has been amply verified (at least as regards the two first). But perhaps the most important fact which has been brought to light is that there undoubtedly exist families of comets following almost exactly the same path in space. Formerly identity of path was considered conclusive evidence of identity in the objects, but we can no longer say this. Tebbutt’s comet of 1881 was moving in almost exactly the same path as the comet of 1807 for which Bessel in a classical discussion had deduced a period of 1,539 years. Fortunately Tebbutt’s comet was visible fora long time and the observations of it proved that it was moving in an orbit of about 3,000 years period, so that it was not a return of the 1807 one. Again the Southern comet of 1880 followed a path almost identical with that of the great 1843 comet which was visible in broad daylight near the sun; and the great comet of 1882 and the first of 1887 were also moving in this same orbit—yet they are all distinct bodies though undoubtedly members of the same family. It must be remembered that the comets in this group pass close to the sun’s surface and right through the corona; and though observation shewed that the 1882 comet had not suffered the slightest retardation in doing so, (thus giving the final blow to Encke’s resisting medium), yet. several faint nebulous masses were ‘observed after perihelion travelling along with the comet and at some little distance from it, which had evidently been torn away from the main body. Thus it is not difficult to imagine that the comets of ’43,’80 and ’87 were separated from the original comet at some previous passage through perihelion ; and indeed it seems to me that we may go further and conjecture that the °43 comet was separated from the parent body (the remains of which I take to be the ’82 one) at an earlier approach to the sun than the ’80 and ’87 comets, partly on account of its much greater brilliancy and partly because its tail belongs to Bredichin’s type I, corresponding to hydrogen, the lightest known element, while that of the 80 comet belongs to type Ll, the hydro-carbons. An interesting and instructive observation, unique in the history of astronomy, was made by two observers atthe Cape in 1882: the ““ Great September Comet’ was followed in the telescope till it reached the sun’s limb, when it disappeared completely though it was passing, in front of the sun’s disc. Shortly before the transit’ it shewed as a brilliant circular disc 4” in diameter, but the disappearance proved
al President’s Address. [ Aug. 29,
that it was nota solid globe of this size but only an aggregation of small bodies, which were sufficiently small and sufficiently far apart not to be visible on the sun. This comet and the one discovered by Wells earlier in the year revealed a new fact in the chemical con- stitution of these bodies; when they were near the sun the usual hydro-carbon bands seen in the spectroscope were entirely replaced by the bright sodium lines, and these again disappeared and gave way to hydro-carbon bands as the comets receded from perihelion. I have already mentioned that there is a group of comets connected in some way apparently with the planet Neptune and which have a period of about 70 years, one of which is Halley’s famous comet. A second was discovered in 1812 by Pons, and a third in 1815 by Olbers ; these have both presented themselves to view again, the former in 1883 the latter in 1887; the other members of the group are not yet due. The connection between meteor-swarms and comets is now well established, viz. that these swarms result from the disintegration of a comet ; and each return to perihelion of what was once Biela’s comet gives us a brilliant shower of these small bodies. The last was in November 1888,
STARS.
We are at least beginning to feel our way, with no uncertain steps, to the determination of the distances of the stars from our system. In 1884 Gill and Elkin published the results of their heliometer observations of the parallax of Southern Stars—a classical investi- gation far surpassing all previous attempts in accuracy and extent. It is a pleasing fact for Cape astronomers that they confirmed the substantial accuracy of Henderson’s value for the parallax of a Centauri, deduced 50 years ago from his own observations with the Cape mural circle. This star still remains, with our present know- ledge, the nearest star to us; while 8 Centauri refuses to yield any sensible parallax. Asaph Hall and Ball have also contributed very valuable work on this question ; and the new Cape heliometer is now actively at work on it. Several important catalogues of star-places have been published in the last few years, notably Stone’s Cape Catalogue of 12,441 stars, and Gould’s Cordoba Catalogue of 32,448 stars. Each of these gigantic pieces of work was carried through in a few years, Stone’s in 10 years, Gould’s in 15. Up tothe year 1870 our knowledge of the accurate positions of stars in the Southern
1888. | President's Address. xli
‘Hemisphere was of a very meagre description ; but now, thanks to the labours of these two astronomers and their assistants, we can safely say that the southern half of the sky is better surveyed than the northern; and it will remain so till the publication of the catalogue of stars to the 9th magnitude now being made under the direction of the Ast. Gesellschaft and by the co-operation of fourteen observatories in Europe and America. In 1860 Dr. C. H. F. Peters commenced the enormous task of forming maps giving the positions of all stars down to the 14th magnitude situated within 380° on each side of the ecliptic. Part of the work was finished in 1882 and will prove invaluable in the search for minor planets ; but the photographic survey of the sky, which was resolved on last year and which will shortly be commenced, will replace all similar work in the future. ‘Such a survey, including all stars to the Sth magnitude, is now -approaching completion at the Cape Observatory, and the work of ‘measuring the pkotographs and cataloguing the stars is being done by Prof. Kapteyn of Groningen. Variations in the brightness of stars have always attracted much attention and there are many striking “instances of such changes, e.g., the wonderful , Argiis which 50 years ago blazed out till it was the brightest star in the southern skies, while now it is below the limit of visibility to the unaided eye. Extensive catalogues have recently been made giving “accurate determinations of the magnitudes of the stars, by Gould for the Southern Hemisphere and by Pritchard and Pickering for the Northern. -Gould’s estimates were made with the naked eye or by the help of an opera-glass; Pritchard’s by means of the “‘ wedge photometer,” a wedge of neutral-tinted glass made to slide in front of the eyepiece -of the telescope till the point of extinction of the star’s light is reached ; Pickering’s by a polarising apparatus used in such a way -as to reduce the light of the stars to equality. Successful photographs -of stellar spectra were obtained by Huggins in 1879 and by Cornu in 1886, and this work is now being carried on at the Harvard Obser- vatory on an extensive scale. A large prism placed in front of the -object-glass gives at once the spectra of all the stars in the field of view of the telescope; and in January 1886, with an exposure of 34 minutes a photograph was obtained shewing the spectra of 40 _stars in the Pleiades, which nearly all belonged to the same type. Determinations of the velocities of stars in the line of light have “been regularly kept up at Greenwich and by Vogel, but the excessive difficulty of the observation has prevented the results hitherto obtained
xlii President's Address. (Aug. 29,
from being as concordant as could be wished. The observation consists in determining the displacement (due to motion to or from the earth) of a line in the star’s spectrum as compared with the same line given by an artificial hight; but the smallness of the displacement and the unsteadiness of the stellar line caused by the earth’s atmos- phere almost make a satisfactory observation hopeless. Here again photography promises to come to our assistance, the sensitive plate does what the eye cannot do, it shews the accumulated effect of the various positions of the unsteady line by a space the centre of which: corresponds to the mean position of the line. There is very little’ doubt that this method, which was suggested and has already been successfully tried by Vogel, will entirely supersede the older one of. eye observations. ;
On the many other applications of photography to astronomy I shall not dwell, as it is only a short time ago that we had an exhaustive account of them from Dr. Gill; but it is abundantly evident that the co-operation of electricity and photography have: completely revolutionised the older astronomy and opened up new and extensive fields of research.
Many new observatories have sprung into existence in the last 12 years, one I am glad to say in South Africa, viz., the Natal Obser- vatory at Durban. The latest and greatest is the Lick Observatory in California ; it is situated on Mount Hamilton at an elevation of 4,200 feet above the sea, it possesses the largest refracting telescope in the world and an excellent climate, and with a staff of experienced observers it has a great future before it.
There are numbers of minor points in which substantial progress has been made, but an account of them all would filla volume. I have endeavoured to lay before you the more important ones, and I hope I have succeeded in giving you some idea of the problems that have been solved in the last few years and of the unceasing activity~ and earnestness of the devotees of the noblest of sciences.
MINUTES OF PROCEEDINGS.
Ordinary Monthly Meeting. WEDNESDAY, AuGusT 29, 1888.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESIDENT, 1N THE CHAIR.
Mr. W. C. Meredith, M.A., and Mr. J. Martin were elected Ordi- nary Members of the Society.
Mr. Trimen read some notes on the teeth of a whale, JMesoplodon Layardiu (Gray), of very peculiar form, and exhibited specimens.
Mr. Woods exhibited some photographs of lightning flashes taken during the recent thunderstorm, and read some notes thereon.
After some remarks by Messrs. Finlay, Marloth and MacOwan the meeting closed with a vote of thanks to Messrs. Trimen and Woods.
Ordinary Monthly Meeting. WEDNESDAY, SEPTEMBER 26, 1888.
Mr. W. H. Finuay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.-
Mr. D. C. Andrew and the Rev. D. P. Faure were elected Ordinary Members of the Society.
Mr. C. Ray Woods exhibited some photographs of lightning flashes taken during the recent storm.
Messrs. Fisk, Finlay and Péringuey took part in a short discussion.
Ordinary Monthly Meeting. ~ WEDNESDAY, OCTOBER 31, 1888.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
Prof. MacOwan exhibited a specimen of Jmanthes retzioides, Benth., found by Eklon, Poppe and R. Templeman. This specimen with four or five others was found near Waterfall Farm, Tulbagh.
xliv Minutes of Proceedings.
The Rev. G. H. R. Fisk read a note about the tortoise exhibited by him at the meeting held on June 27 last. It had been ascertained that the tortoise referred to was not a new species but merely an anomalous species of Testudo semiserrata.
The Rev. Dr. Kolbe then read Mr. Hammond Tooke’s paper on “The Star-lore of the S.A. Natives,” to which was appended some notes by Dr. Kolbe senior.
The Rev. Dr. Kolbe stated that the Damaras have a word for Cemets, viz., ‘the long thing which makes people enquire ” ; the milky way they call “rising steam.” ‘They once knew something about meteors. ‘The Wen. Archdeacon Lightfoot said that the coloured races in Cape Town have no traditions about the stars.
The Rev. G. H. R. Fisk said that every endeavour should be made to secure photographs, &c., of old Bushman paintings and specimens of remains.
The Rev. G. Stegmann had tried to get specimens from caves in Oudtshoorn. In several cases, at a depth of four or five feet he found ivory arrow-heads stained blue, and a bar of horn, bone needles, pots, teeth of animals, a pipe with three bowls running into one stem, made of clay.
A vote of thanks to Mr. Tooke and Dr. Kolbe closed the proceedings.
Ordinary Monthly Meeting.
WEDNESDAY, NOVEMBER 28, 1888.
Tue Rev. Proressor Foor In THE CHAIR.
The undermentioned gentlemen were duly elected Ordinary ‘Members of the Society :
Mr, Alexander Mair, Mr. W. J. Murphy, Mr. L. C. F. Moodie.
The Rev. G. H. R. Fisk exhibited a snake and a tortoise.
The Secretary read Mr. Hammersley-Heenan’s paper “On the action of Teredo Navalis, &c., on the piles of Port Elizabeth Jetty.”
Mr. D. C. F. Moodie read a paper on “The Northern Gold Fields of South Africa,” the completion of which was postponed till next meeting.
Minutes of Proceedings. xlv-
Ordinary Monthly Meeting.
WEDNESDAY, Frspruary 27, 1889.
Mr. W. H. Fintay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR..
The undermentioned presents were announced and the thanks of the Society voted to the donors : 7
Geological and Natural History Survey of Minnesota, 15th Annual Report, 1886.
Geological History Survey of Minnesota, Bulletins Nos. 2, 3, 4.
Bulletin of the California Academy of Sciences, Vol. 2, No. 8.
Proceedings of the American Philosophical Society, Nos. 126, 127.
Smithsonian Report, 1885, Part 2.
Mr. Bolus exhibited an orchid found (Jan. 2) on Constantia Berg by Mr. Bodkin. It had been found about fifty years ago near Caledon, and two years ago near Stellenbosch—now, for the first time, in the Cape Peninsula.
The Rev. G. H. R. Fisk exhibited specimens of the complete series Homopus Areolatus, Homopus Femoralis and Homopus Signatus —the latter exhibited here for the first time alive. The specimen is. one of three captured in Clanwilliam. The other two have been sent to the Zoological Society of London.
The Rev. G. H. R. Fisk further exhibited a totally black shell of the: tortoise, Chersina Ungulata or Angulated Tortoise, found at Verkeerde Vley near Touws River. The living animal was also totally black.
Mr. Trimen read a letter from Mr. Geo. Romanes requesting that some members of the Society would take up experiments on the bite . of scorpions. ‘The question to be decided was whether the poison glands are able to absorb the poison of bites inflicted by other scorpions, that is to say, would scorpions if deprived of their poison glands survive the bites of others.
Prof. Guthrie brought forward a table for calculating heights from barometric readings. Assuming the height of Kimberley as known, he deduced a factor by the means of which the known and calculated
heights of Aliwal North, Cradock and Graham’s Town were shown to- agree very closely.
xlvi Minutes of Proceedings.
Mr. Finlay, Dr. Gill, Mr. Fourcade (a visitor) and Mr. Howard (a visitor) took part in the short discussion that ensued.
The President, in Mr. Moodie’s absence, proceeded with the reading of Mr. Moodie’s paper on the Northern Gold Fields, and a vote of thanks to Messrs. Guthrie and Moodie closed the proceedings.
Ordinary Monthly Meeting.
WEDNESDAY, Marcu 27, 1889.
Mr. W. H. Finuay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
Messrs. G. P. Moodie and F. 8. Lewis, M.A., were duly elected Ordinary Members of the Society.
Mr. R. Trimen exhibited specimens of the “ Silver Moth” (Leto Venus), from the Knysna, district of the Cape Colony, where they had been collected by Miss Newdigate, and by the late Mr. W. K. Newdigate, near Forest Hall, Plettenberg Bay.
He called attention to the great size and beauty of this splendid. insect, features the more remarkable because the moth belonged to a family (Hepialide) of which the great majority presented small stature and very dull colouring. Specimens of three South African species of Hepialide were exhibited in illustration of the ordinary members of the family.
Another point of interest was the very limited district which the Silver Moth inhabits. No examples are recorded to have occurred in the Eastern Districts of the Colony, Kaffraria, or Natal; nor is it known from the interior or from any part of Tropical Africa. Miss Newdigate, who has had a long and intimate acquaintance with the insect, states that the Western limit of its range known to her is ‘Oakhurst, between George and Knysna and the Eastern limit Storm River. The Zitzikamma forest tract may thus be said to constitute the only habitat of Leto Venus, though this is rendered difficult to understand by the fact that the caterpillar’s only known food is the wood of the Keurboom (Virgilia Capensis) a familiar leguminous tree, with sweet scented pink-and-white flowers which has a wide distribution in the South of the Colony.
The moth is only found from the middle of January to the middle of March, and between the hours of four and six p.m.
Minutes of Proceedings. xl vil
‘The moth was figured in 1782 by the well-known Dutch author, Cramer, on pl. 286 of his “ Uitlandische Kapellen (Papillons Exo- ‘tiques).”” (Specimen probably collected by J. A. Ange, botanical collector on an expedition in Governor Tulbagh’s time (latter died in 1771), who is known to have collected many of the insects then first -sent to Europe.) Cramer is quite enthusiastic on the splendour of its silver markings ; but he was not contented with its extremely short -antennee (a characteristic feature of the family) and therefore made them in his figure of (what he judges to be) a suitable length! A ‘tolerable wood cut of the moth is given on pl. 8 of Vol. II. of the -“ Papillons”” of Chenu’s ‘“ Encyclopédie d’ Histoire Naturelle” (1857), but no good figure of this grand moth has yet been published.
Mr. Bolus suggested that in all probability its habitat was deter- ‘mined by the meteorological conditions of the Knysna.
Mr. Péringuey exhibited some beetles from the neighbourhool of Walfisch Bay—a set of three which he had only received a few days previously from Mr. Carrington Wilmer had enabled him to settle the identity of Eurymorpha Cyanipes with Eurymorpha Mouffleti. He also exhibited a specimen of the extremely rare Mantichora Ludovict,
which seems to be represented in European collections by ove example only. Healso exhibited a small tiger beetle, Coandela nilotica, fouud (for the first time in South Africa) by Mr. Carrington Wilmer: this insect has been found from Cairo to the Blue Nile, in Senegambia, and now in South Africa. |
The President then read Mr. H. C. Schunke’s paper “ On a Method of preparing Silhouettes for the purposes of Anthropology.”
In the discussion that ensued Messrs. Péringuey, Bolus, MacOwan, Finlay and Fisk took part and the proceedings closed with the usual -vote of thanks.
Ordinary Monthly Meeting. WEDNESDAY, APRIL 24, 1889.
Proressor GuTHrik£, LL.B., In THE CHAIR.
Tae undermentioned presents were announced, and the thanks of the Society voted to the donors :
Victorian Year Book, 1887-8.
xIvili Minutes of Proceedings.
Catalogue of Canadian Plants, Part 4, Endogens. Transactions and Proceedings and Report of the Royal Society of. South Australia, Vol. X.
Mr. Bolus exhibited a specimen of Vaccinium exul, a new species: of that plant, found at the Devil’s Kantoor on the Drakensberg, 30 miles from Barberton, 5,400 feet above sea level. No plant of that genus had ever been found previously so far south in the Southern Hemisphere. It was noticed that the fringe of mountains which ran round a large portion of Africa was the pathway of connection of - plants. It was always on the mountain ranges that Northern Hemis- phere plants were found in the Southern Hemisphere and vice versa. When this migration of plants took place had never yet been deter- - mined.
Prof. Guthrie stated that the discovery of this plant was especially interestipg as a new fact in the geographical distribution of plants from which the history of the world could be written.
Dr. Gill then gave a most interesting account of recent results of the Geodetic Survey of South Africa, which had now been completed from Natal to Port Elizabeth. He first gave a short history of various earlier attempts at survey in the Colony, and then proceeded to describe the method of measuring the base lines, the instruments employed, and the accuracy obtained. He stated that the Transvaal had voted £10,000 for a similar survey and it had been proposed that such a survey should be carried out in Bechuanaland, so that soon South Africa would have a survey that would be a eredit to the country.
Mr. Marquard, Prof. Guthrie, and Mr. Justice Buchanan made some remarks to which Dr. Gill replied and the meeting closed with
the usual vote of thanks.
Ordinary Monthly Meeting.
WeEDNESDAY, May 29, 1889.
Mr. W. H. Finuay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR.
The African traveller and hunter, Mr. F. C. Selous, gave a most. interesting account of a journey made by himself beyond the Zambesi to the country of the Mashukulumbwe.
Minutes of Proceedings. xlix
Ordinary Monthly Meeting.
WEDNESDAY, JULY 31, 1889.
Mr. W. H. Finuay, M.A., F.R.A.S., PRESIDENT, IN THE CHAIR. 9 ?
The undermentioned presents were announced and the thanks of the Society voted to the donors :
Bulletin de la Société Impériale des Naturalistes de Moscou, 1888, No. 3.
The. American Anthropologist, Vol. I. pts. 2, 3, 4, Vol. II. pt. J.
Journal of the Cincinnati Society of Natural History, Vol. XJ.—4.
Proceedings of the American Philosophical Society, No. 128.
A Grammar of the Kwagiutl Language (Iransactions of R.S. of Canada, Vol. VI., Section II.)
Feuille des Jeunes Naturalistes, No. 225.
Mikrographie der Mitteldermdrtise (Leber) der Mollusken.
Versteinerungen der Cambrischer Schichtensy stems.
The Rev. G. H. R. Fisk exhibited two specimens of manganese markings on sandstone. )
The President then read Mr. Carrington Wilmer’s paper on ‘‘ The _ Relation of the Sand-dune Formation on the South-west Coast of Africa to the Local Wind Currents.”
Mr. Péringuey said this large belt of sand extended down the coast to Blaauwberg, and that from Cape Blanco to the Congo there was a similar stretch of sand. He did not believe that these sand- ‘dunes were of recent origin for the following reason: ‘There was one genus of Coleoptera common to both the East and West Coasts -of Africa, and the one found on the West Coast possessed a special formation of the legs for moving quickly over sand. This formation must have taken ages to bring about.
Messrs. Fisk, Gill, Marloth, and Prof. Seeley (a visitor) -also took part in the discussion.
A vote of thanks was accorded to Messrs. Wilmer and Seeley.
Mr. Finlay (President) announced the discovery of a new comet ‘by Davidson, Queensland, on July 22. It was observed at the Cape on July 25, 26, 27, its orbit computed, and cabled to Kiel. The comet has a bright round nucleus, almost star-like; surrounded by faint nebulous matter, and has a short faint tail. It was near the
earth when discovered, about one-third of the distance from earth E
l Minutes of Proceedings.
to sun, and had passed perihelion only 34 days, and as it is going away now from both earth and sun it will not become a conspicuous object. It is just visible to the naked eye.
Annual General Meeting. WEDNEsDAY, AuGuUST 28, 1889. Mr. W. H. Fintay, M.A., F.R.A.S., PREsIDENT, IN THE CHAIR.
The reports of the Secretary and Treasurer were read and adopted.
The Members present proceeded to the election of a President and Council for the ensuing year, with the following result :—
President: L. PErinauty, F.Z.S., Memb. Ent. Soc. Lond. Council: D. Gitt, LL.D., F.R.S., F.R.A.S. P. MacOwawn, B.A., F.L.S. H. Bouuvs, F.L.S. W.H. Finuay, M.A., F.R.A.S. F. Guturik, LL.B. R. Marztota, M.A., Px.D. R. TrimeEn, F.R.S., F.L.8S., F.Z.S. Hon. C. A. Situ, M.A. J. H. M. Beck, M.B. Rev. G. H. R. Fisx, C.M.Z.S.
Mr. Finlay then delivered the President’s address, at the conclusion of which a vote of thanks was proposed by Sir H. de Villiers and carried unanimously.
REPORT OF THE PROCEEDINGS OF THE SOUTH AFRICAN PHILOSOPHICAL SOCIETY
DurtmNG THE YEAR Enpine 1889, Jury 31.
1. Since the last Annual General Meeting nine Ordinary Monthly Meetings have been held. The average number of Members present nas been ten, and of visitors eight, making an average total attend- ance of eighteen. :
2. At the Ordinary Meetings ten papers have been read in the subjects Anthropology, Astronomy, Engineering, Geography, Geology, Meteorology and Zoology. Notes and shoiter communica- tions on a variety of subjects have also been brought before the Society ; brief accounts of these will be found in the Notes of Pro- ceedings. |
3. Twenty-six presents of books have been received. A list of these will be found in the Proceedings of the Society. There has. been a considerable demand for the publications of the Society lately,. and a corresponding increase inthe number of presents received. A bookcase has been placed in the meeting room, one key to which is kept by the Secretary and the other at the Commercial Exchange. Access can be had to the books by Members at any time on applica- tion to Mr. Ellis at the Commercial Exchange. In case of a member: taking any book away notice should be given to the Secretary.
4, During the year ten Ordinary Members have been elected and one has resigned. The total number of Ordinary Members is seventy- six, and of Corresponding Members twenty-three.
5. Volume IV. part 2 and Volume V. part 1 have been issued to Members and distributed to a number of Scientific Societies in various parts of the world. | DAVID GILL,
General Secretary’
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ANNUAL ADDRESS TO THE MEMBERS OF THE SOUTH AFRICAN PHILOSOPHICAL SOCIETY,
On THE 28TH Avcusrt, 1889,
By THE PresipEntT, W. H. Finuay, M.A., F.R.A.S.
Ir has usually been the custom in our Society for the President at the end of his second year of office to review the work accomplished during the two years of his presidency. As however my two immediate predecessors in this chair found it irreconcilable with their other duties to accept the honour of re-election at the end of their first year, it fails to my lot to review our work for four years in order to maintain continuity.
We have had a large number of interesting exhibits at our meetings which have elicited much useful information from members. In the first rank of the exhibitors must be placed the Rev. G. H. R. Fisk, whose energy in this direction I would like to see imitated by many more of our members. Among Mr. Fisk’s exhibits I must specialiy refer to a complete series of the homopus tortoises, viz., homopus areolatus, hom. signatus, and hom. femoralis, the only complete set which has I believe been shewn alive, and of which hom. signatus was new to the collection of the Zoological Society of London. Also to a second specimen of ¢testudo Fiski, the only other one known having been discovered by Mr. Fisk towards the end of 1885. The discovery of this specimen and of testudo Trimeni led Mr. Boulanger to a complete revision of the South African tortoises allied to Testudo geometrica, with the result that seven well-marked. species could be distinguished. Mr. Fisk had also the pleasure of discovering a new snake which was described by Mr. Boulanger in the Proceedings of the Zoological Society of London May 3, 1887, and was named Lamprophis Fiski.
Mr. Trimen shewed us a perfect specimen of the rare Lycoenide butterfly, Aphnoeus Hutchinsonii. This species was previously founded on a single worn example of the male captured in 1886.
liv President’s Address. [Aug. 28,
To Mr. Péringuey we have been constantly indebted for exhibits of beetles and for explanatory remarks on them. One recently shewn by him, a small tiger-beetle (Ciandela Nilotica) has a very wide habitat: it has been found from Cairo to the Blue Nile, also in Senegambia and the specimen shewn was found by Mr. Carrington- Wilmer for the first time in South Africa.
Mr. Bolus exhibited a specimen of vaccinium exul which he had found about thirty miles from Barberton, which was very interesting as being the only plant of the order known in extra-tropical Africa ; no vaccinium having hitherto been recorded south of the Tropic of Capricorn in any part of the world.
To Mr. MacOwan we are indebted for a specimen of Ixianthis retzioides, a rare and little known plant. He was fortunate enough to procure a number of specimens and a good supply of ripe seed, so that we may hope that this fine plant will be introduced to culti- vation. Mr. Woods shewed us some photographs of lightning- flashes which be had taken during a thunderstorm. The appearances presented were curious and perplexing and it is highly desirable that further investigations should be made. Unfortunately for us (7.e., so far as the study of these flashes is concerned) our opportunities are few at the Cape for such work, but perhaps some of our friends in the Eastern Province will take up the question. The interest attaching to such photographs at the present time is very great as it has been recently asserted that in some kind of storms the duration of the flash is not by any means infinitesimal.
Among the papers presented to the Society and printed in our Transactions the most important are Mr. Péringuey’s second contri- bution to the South African Coleopterous Fauna and Mr. Bolus’ orchids of the Cape Peninsula. Mr. Péringuey’s paper is in con- tinuation of the one published in Vol. IV. of our Transactions : the present contribution gives an exhaustive description of 187 Coleoptera, several of which are new to science and the paper is illustrated by four plates, figuring forty-five specimens. ‘The previous contribution described 100 specimens and I believe that Mr. Péringuey has a third one well advanced. Mr. Bolus describes botanically 102 orchids growing on the Cape Peninsula, arranging them in groups and stating where they are to be found and their period of flowering. It will be seen that several of the species described were new to science when discovered by Mr. Bolus or his botanical friends, among whom Jam glad to say are two of our members, Prof. A. Bodkin and Dr.
1889. ] President's Address. lv
Marloth. In fact out of the 102 species therein enumerated thirty- one had never been previously recorded as oceurring in the Cape Peninsula and of these fifteen were new to science. The book is enriched with thirty-six exquisite drawings, partly coloured, of orchids which, with the exception of four or five, have never been previously figured. The immense value of these drawings makes us wish the whole series might have been illustrated in the same way, but the funds of the Society J am sorry to say will not allow of the expenditure, although Messrs. Péringuey & Bolus have borne a large amount of the cost of these plates themselves. Such papers as these, the result of patient work and a profound knowledge of their subject, will enable our Society to take a high rank among the scientific societies of the world.
During the period I am. reviewing the presence of Phylloxera Vastatrix was detected at the Cape and we have heard now and again from Mr. Péringuey of the progress made in checking it. Knowing, as we do, Mr. Péringuey’s profound knowledge of Ento- mology it is no surprise to fiad that his treatment of the Phylloxera and precautions against its spread have received the most unqualified approval from the expert who was invited to report on them in deference to the clamour of an ignorant public. I wonder when the people of this colony will understand that a man who has devoted the best part of his life to a particular study and has attained a reputation in it knows more about it than the hundred and one amateurs who with only a most superficial acquaintance with the subject are ever ready to give their opinion.
- Looking at the position of our Society generally 1. think we may feel satisfied, but not more than satisfied. Our numbers have increased during the last year, but on the average they remain much the same. Owing to the meetings being held in Cape Town the Society is chiefly composed of members who reside there, in fact only -ten per cent. of our members reside at any distance from Cape Town. Now this is not as it should be; are there no lovers of science at ‘Stellenbosch, where we have not a single member, Graham’s Town or Port Elizabeth ? There is, however, a reason for our not numbering many members outside Cape Town, and that is that the subscription is the same for all ordinary members irrespective of place of residence. Consequently a would-be member living at a distance ‘finds that he cannot attend the meetings but that he can buy the Society’s Trans- _actions for a few shillings and so he does not join the Society. I
lvi President’s Address. [Aug. 28,
think this might be met by a reduction in the subscription for members residing more than twenty miles from Cape Town, and I intend to bring a motion to this effect before the Council ; if it is carried I hope it will result in a large increase of our numbers.
But J ask the members we have to do more than they have done in the way of providing food for the Society’s meetings. I find that out of our present members 22 per cent. have contributed papers of some length during the last four years, and this is perhaps as high an average as can be expected ; but that, including these papers, only 27 per cent. have contributed anything, paper or exhibit, to our meetings. This isa very low proportion, and I hope that members will help us to remove this reproach by bringing more exhibits and by short notes on any point that seems to them worthy of notice. There appears to be a feeling that for a paper to be accepted by the Philosophical Society it ought to occupy at least half-an-hour in reading, but this is an utter mistake. A note of half- a-dozen Jines on some interesting phenomenon would be just as welcome and would probably give rise to a valuable discussion,
I should have been glad to bring before you a review of the pro- gress of science in other parts of the world during this time, but am not unfortunately equal to the task; so that I must ask your indulgence if I act up to the old motto ne sutor ultra crepidam and give you some account of the progress in that braneh of science with which I am inore particularly acquainted.
ASTRONOMY.
The most striking and important advance during the last year or two in this departnsent is the successful application of photography to astronomical measurements. Astronomical pictures had been taken- many years ago, ¢é.g., of the moon, planets and bright nebulae, but it: has only quite recently been shown that a photographic plate exposed. for a few minutes will furnish as good a position of a particular star with reference to the surrounding stars as a single observation with a large Transit-circle. Of course there are many precautions to be taken in the exposure of a plate to secure this degree of accuracy and laborious researches to be executed on each plate to arrive at the results, but the certainty that this accuracy can te attained will, cause a revolution in meridian observing. The meridian circle will be- no longer devoted to the observation of vast numbers of stars as has.
1889. | President's Address. vii
hitherto been necessary, if anything like a decent knowledge of the
starry heavens was to be hoped for ; this work will now be relegated
to photography. But it must not be supposed that the meridian
circle is superseded and deposed : on the contrary it must return to its
more legitimate work, viz., the determination of accurate star-positions.
To reduce the stars on any of these plates it is necessary to know the
positions of a fair number of the brighter stars on it, and from these
the position of all the others may be determined ; but to determine the
position of these few standard stars or zero points, we must fall back
on the meridian circle. It is certain therefore that in the future the
work of the meridian circle will be confined to determining with the
utmost possible accuracy the co-ordinates of certain standard stars
which will be used as zero points ; observations will be multiplied
under conditions calculated to destroy every conceivable systematic
error ; more time and care will be given to examining the flexure and
instrumental adjustments, with their variations, of the instruments ;
more extended and refined investigation of the constants of astronomy
will be made, and every true lover of exact astronomy will be rejoiced that more time and study will be available for these questions
now that the meridian circle is freed from its uncongeuial task, taken
up under dire necessity, of zone-observing. And that I do not make’ these assertions without cause the following facts will prove: If we
take the Right Ascensions or Declinations of some standard star as’ determined from a large number of observations at several first-class’ observatories we find differences between them; small certainly, but’ still larger than should exist. What is the cause of these differences ? Unknown errors of refraction, flexure, personal equation depending on
the magnitude of the star, proper motion, &c., &¢. The removal of
these discrepancies is of primary importance; many attempts have
been made to combine the results of various observations into one system, but as they mainly consist of adopting the results of one or
two observatories as eminently free from systematic error and reducing
others to them, this plan does not commend itself to my mind as
satisfactory. Our distinguished visitor at the Observatory, Dr.
Auwers of Berlin, has pre-eminently shone in this work of deducing #
standard system of star-places, but even he finds that recent obser-
vations at the Cape shew that there are errors still outstanding in our
refraction tables. Let then to photography be given the task of
determining the relative positions of all stars visible in a telescope and.
to the meridian circle its proper work of determining zero-points..
“Avil President's Address. - [Aug. 28,
PHOTOGRAPHY AND ASTRONOMY.
We have heard so fully from our Secretary, the Astronomer-Royal, about the application of Photography to Astronomy that I shall not enlarge on the subject to-night, but will only refer to one or two points in connection with it. Probably many of you are aware that for several years past regular observations have been made, chiefly at Greenwich and Rugby, to determine the motion of stars in the line of sight, as it is called, 7.e., either directly towards us or from us. This is done by measuring the amount of the displacement of some particular line in the star’s spectrum caused by a motion of approach or recession. Naturally the amount of this displacement is very small, and owing to this and the tremors in the image caused by the atmosphere, the observations are very difficult and liable to large accidental errors ; indeed, I remember a distinguished astronomer telling me it was the most difficult observation he had ever tried to make. This being the case we have had to be content with results differing widely among themselves but probably something like right in the mean of a large number. For example, here are some Greenwich results for the motion in miles per second of Capella: + 4, + 19, + 52, + 38: + 538, — 4, — 55, + 42, — 21, + 2, + 380, the mean of all being + 16. |
Quite recently Dr. Vogel, at Potsdam, has photographed the spectrum of this star together with that of an artificial light, and the results of his measures on ten nights vary only from + 14 to + 18. The agreement between his results and the mean of the previous ones is satisfactory, but what a difference in the accuracy of the indi- vidual measures ! What a gigantic stride in advance are these photo- graphic results over all that had preceded them! Now at least we may feel sure of arriving at a definite knowledge of the motions of approach or recession of the brighter stars with a fair prospect of accuracy.
THE SOUTHERN SKIES.
The preliminary photographic survey of the Southern Skies which has for the most part been carried out at the private expense of the Astronomer Royal at the Cape, was completed a few months ago, and the positions of the stars are being measured from the plates by Prof. Kapteyn of Groningen. It is satisfactory to know that the plates bear the test of measurement well, and the result will be a catalogue of all the stars in the southern hemisphere down to 95 magnitude, the
1859. ] President's Address. lix
‘place of each star being correct to within about 5". You are all -aware that the great international scheme for securing a photographic chart of the whole sky down to the 14th magnitude has been successfully floated and that the Cape will have a share in the work ; -our observatory and dome are up at the present time and work will be commenced in a few months. With the new telescopes, exposures of a few minutes will be sufficient to secure stars to the 14th magni- tude, and exceptional precautions are taken to secure accuracy.
I will only mention one other result of recent photography, viz., in connection with long exposures. A good many years ago Prof. Tempel announced that he could see a faint large nebula extending to _a considerable distance from the star Merope in the Pleiades ; such an announcement naturally caused the most lively interest, but the evidence in favour of its visibility was most conflicting ; some of the best observers with large instruments were utterly unable to detect anything of it, and again it was seen and sketched similarly to Prof. Tempel’s description by others. The balance of probability, however, I think, was in favour of its non-existence. A few years ago Mr, Isaac Roberts, a Liverpool merchant who has devoted his spare time to astronomy, took up the subject of astronomical photography with the best instrumental adjuncts that money could supply. He has devoted his attention chiefly to the results of long exposures and has reaped truly astonishing success. With an exposure of from three to four hours he finds that not only is the Merope nebula a reality, but that the whole region of the Pleiades is swarming with nebulous matter ~which is quite invisible to the naked eye; the photographic plate recording the accumulated energy of these faint masses of light which are quite unable to affect the retina of the eye.
Mr. Roberts has since shown some wonderful results from long exposure and there is no doubt but that there is a rich harvest
to be gathered in this direction.
AT THE OBSERVATORY.
The new Heliometer at the Observatory has been at work now for about a year and a half: it has been employed chiefly by Dr. Gill for the determination of stellar parallaxes. With it he has -accumulated material for the determination of the parallax of a dozen stars varying from the Ist to the 4th magnitude, and a similar work -has been carried out at Yale College Observatory for the Northern
lx President's Address. [Aug. 28,-
hemisphere by Dr. Elkin. ‘The Heliometer was also used last October and November for a determination of the sun’s distance by obser- vations of the minor planet Iris by Dr. Gill and myself, and again during the last three months of the minor planet Victoria by Drs. Auwers and Gill, who have secured over 3,000 observations. The degree of accuracy that can be secured with this instrument is truly astonishing, and if we are fortunate enough to secure a sufficient number of corresponding observations in the Northern hemisphere Iam confident that the vexed question of the Sun’s distance will be settled within very small limits from these observations.
Asan instance of what this instrument is capable of, I will quote some results given by Dr. Gill in a paper read before the Royal Astro- nomical Society in 1888. He gives some measures in that paper of g Centauri from a couple of faint stars at nearly equal distances on opposite sides of it, and all he is concerned with for the determ- ination of the parallax is the difference of these distances ; but taking the sum of these distances amounting to about 10,000 seconds of are the probable error of this very considerable distance from a single’ observation is only 0:2 of a second of arc,
GEODETIC SURVEY. .
The Geodetic Survey of South Africa has been gradually progressing: under the able management of Major Morris, R E. I mentioned in my address last year that an unexpected discrepancy had been found: between the Geodetic and Astronomical latitudes in the neighbourhood” of Port Elizabeth. This has been most carefully investigated by Major Morris since then and he finds that the discrepancy extends: to several places in the neighbourhood. Port Elizabeth and Coega Kop shew discrepancies of nearly the same amount and sign, while Zuurberg and Berlin shew as much discordance in the opposite direction. It would seem tbat somewhere within the area included by these points the density of the underlying strata is considerably greater than the average density of the earth: the station at Driver’s Hill seems to be very near the line of no discordance. Similar anomalies have been found in many parts of the world, but still it is to be hoped that this one will be investigated more fully. A determination of the longitudes of the most important ports on the: West Coast of Africa is being carried out at the present time by Commander Pullen, R.N., and myself. Observations for time are:
1889 ]. President's Address. Ixi
made at each station and then clocks are compared on the same night by signals through the Western cable, which has been placed at our disposal for this purpose by the kind courtesy of Sir Jas. Anderson. The observations for the longitude of Port Nolloth are already finished, and I am at present engaged with those for Mossamedes. In this way the longitudes of Mossamedes, Benguela, St. Paul de Loanda, St. Thomé and Accra will be determined accurateiy : and by signals from St. Vincent it is hoped that a check will be obtained on the difference of longitude Ltetween the Cape and . Greenwich.
COMETS.
During the period I am considering, two comets have been dis- covered at the Cape by two of our members, one by myself in 1886, Septemb:r, and one by Mr. Sawerthal in 1883, January. The one that I had the pleasure of finding was always a faint telescopic comet ; it proved to be a _ periodic one revolving in an orbit of 62 years’ period, and moving in a path very similar to the comet dis- covered by De Vico in 1844. The two comets, however, do not seem to be the same. Mr. Sawerthal’s comet was just visible tc the naked eye when found, and presented some very interesting changes of form during the time it was visible ; its orbit seems to be elliptic but the periodic time is over 2,000 years. Now the discovery of these two
-comets b» men who have little time to give to such work as searching for them gives me the opportunity of making some remarks that have often been in my mind. How is it that in a climate so peculiarly suited for astronomical work as that of South Africa we have practi- eally )« amateur observers ? Mr. Eddie, of Graham’s Town, has a
good + lescope and is always to the fore when a bright comet turns tiv; but with this exception Ido not know of any amateur observer i ‘out! Africa. The climatic conditions are all that could be desired, the nights are never unbearably cold—indeed it is often a relief to be out of doors instead of inside—and yet there is no one to be found with a sufficient liking for astronomy to make a series of observatious. Ido not wish you to understand that I am advocating the immediate formation of a Cape Astronomical Society, though per- haps it will come in time; for the present I think the pages of our own Society’s publications will suffice to place on record any observations that may be made ; but I certainly do wish that some means could be found to arouse @ more active interest in the oldest of the sciences.
President's Address. [ Aug. 28,.
)xit
METEOROLOGY.
Our knowledge of the Meteorology of the Colony is steadily in-- creasing : there are now forty-one stations equipped with a full set of instruments and 3]7 rain-gauge stations. The set of thermometers by which a record of the temperature at each hour of the day is obtained is at work in King William’s Town, after having been observed for two years at Van Wyk’s Vlei. As the result of its stay at the latter place we now know how the average temperature varies. during the twenty-four hours in the various months of the year.. Previously the only place where this was known was at the Obser-- vatory ; and as was expected, the temperature curve for the Karoo differs considerably from that for the neighbourhood of Cape Town ;- for example here the hottest part of the day is about 1.30 p.m., while at Van Wyk’s Vlei it is between 3 to 4 p.m.
The papers read by Mr. Howard and Prof. Guthrie on the reduction. of barometer readings to sea-level are of great value and must receive special mention. This reduction, most- difficult in a country like South Africa but yet essential for any enquiry into isobaric curves, . has for many years occupied the attention of the distinguished meteorologist, Prof. Loomis, in America ; and it seems as though in every country the peculiar factor suited to that country must be sought ; I believe that Messrs. Howard and Guthrie are continuing their investigations in this direction.
A valuable contribution to our knowledge has been recently - published by Dr. Karl Dove, viz., the climate of extra-tropical South . Africa, which is founded to a large extent on the results accumulated and reduced by the Meteorological Commission. He divides the country into a number of belts over which the meteorological con- . ditions resemble one another, and for each of these he discusses the variations of temperature, rainfall and humidity of the air throughout the year.
There is one point in connection with the published results for the . humidity to which I should like to draw attention, that is that they all make the amount of dampness too great. For the convenience of the observers, who are all volunteers, the hour of observation is fixed at 8 a.m. local time. Now at this time, even close to the sea, the degree of saturation is greater than for the mean of the day by 4 or 5 per cent., and I am sure that this amount is considerably exceeded at .
inland stations. I was particularly struck with this during some short .
1889 ]. President’s Address. Ix ilk
visits I paid to Matjesfontcin last winter, where the mean degree of saturation derived from the 8 a.m. observation for the months of July and August was 84 per cent. but in an hour or so it would generally fall to about 60 or 65 and remain so till night. In fact one’s feelings utterly negatived any such degree of saturation of the air as 80 per cent. Ido not believe that this increase of dryness is cancelled by a corresponding decrease during the night, and even if it is the main requirement for a health-station is that the air should be dry during the day-time. I consider, then, to arrive at anything like a proper - estimate of the value of health-resorts up-country an observation of the humidity should be made at at least one other hour in the day. In conclusion, I will quote some remarks of Dr. Dove in connection with the average amount of clouded sky in the South-Western district. He says “ We cannot refrain from a comparison of the amount of cloud here with that of the far-famed sky of Italy. Accord- ing to Hann the mean amount of cloud in Upper Italy amounts in winter from 5 to 6, and sinks in summer from 38 to 4, in Southern Italy from 2 to 38. Even the neighbourhood of Cape Town then is distinguished by a still smaller amount of cloud. Yet the Europeans of South Africa possess neither an art nor a literature of their own: the reason lies in their undeveloped state and home relations (in den unent- wickelten politiken und wirtschaftlichen Verhaltnisse). When future. generations have fostered these branches of human knowledge in that part of the world also, then we shall just as little miss in their pro-- ductions the influence of the bright sky, strengthened by the unbroken mildness of the climate, as among the equally-favoured nations of South Europe.”
LIST OF ORDIN \RY MEMBERS
OF THE
pak Alycan Philosophigul Sogtety.
TCNAe
heysie)
Abercromby, A., M.D.
Anderson, T. J.
Andrew, D.C.
Andrews, J.
-\rderne, H. M.
Atherstone, Hon W. G., M.D., M.L.C. *Beck, J. H M., M.B.
Berry, Dr. Bisset
Biden, A.
Bodkin, A. A., M.A.
Boettger, G. *Bolus, H., F.U.8.
Buchanan, E. J., Hon. Justice
‘ airncross, T. W.
De Villiers, Sir J. H., K.C.M.G., C.J. Easton, J.
Katon, C. R.
Ebden, Hon. A., M.L.C.
Fairbridge, C. A.
Faure, Rev. D. P.
Fisk, Rev. U. H. R., C.M.Z.S. 4FBinlay,W. H., M.A. F.R.A.S.
President.
Foot, Rev. H. M., LL.B.
Fuller, T. HE. M.U.A.
Gamble, J. G., M.A., M. Inst. C.E. *Gill, David, LL.D. F.BS., F.R.A.S.
General Secretary,
Grier, W. M., M. Inst..C.E. Guild, R. K., M.D.
*Guthrie, F. Lu.B., Herman, C. L., M.B. Hewat, Capt., C.M.Z.S. Howard, R. N., M.R.C.S., Eng. Innes, J. K., M.L-A. Kotze, Rev. Dr. J. T. Leonard, J. W., Q.C., M.L.A. Lewis, F. S. Lightfoot, Ven. Archdeacon, B.D. Lindley, J. B., M.A., LL.B.
Marloth, R., Ph. D. acOwan, Prof., B.A., F.L.S., F.H.S. Mair, A. Marchand, Rev. B. P., B.A. arquard, L. Martin, J. -Maskew, F. - eredith, W. C.,M.A. *Merriman, Hon. J. X., M.L.A. Michell, L. Moodie, D.C. F. Moodie, G. P. Molteno, P. A., B.A., LL.B. Murphy, W. J. *Péringuey, L., M. Ent. Soc. Lond. Ponder, 8. N. Robinson, Miss L. A. Rose, J. HE. B. St Leger, F. Y., B.A. aunders, J. Sauer, Hon. J. W., M,U.A. Sauer, H. B. Sawerthal, A. Southey, Hon. R., C.M.G. Schunke, H. C. ‘jS.tberbauer, C. F. 3 lberbauer, J. C. }.vewrignt, J.. M.A., M.I.E.E., C.M.G.
3a th, Hon. C. Abercrombie, M.A., Treasurer.
tegmann. Rey. G. W.
Stewart, T., F.G.S., M. Min. Soe. ‘ait, M. M.
'Yooke, W. H.
'*Pnmen, R., F.R.S., F.LS., F.Z.S)
Upington, Sir. T., M.A., Q.C., K.C.M.G., M.:-..A.
Warton, Major T. G., F.GS. Wie er. L., M.L.A. Woods, C. R.
ee a a ea ae ae ae reas
Those markel * are
Members of the Council.
THE TRANSACTIONS
OF THE
SOUTH AFRICAN PHILOSOPEICAL SOCIETY,
THE WINTER STORMS OF SOUTH AFRICA, ILLUS- TRATING THE VALUE OF CAPE POINT AS A WARNING STATION.
BY
[| READ 28th SEPTEMBER, 1886. ]
On entering into the question of the meteorology of Cape Point,. _ it is intended to show how an isolated peak of medium altitude, inter-. cepting the path of a cyclone, may be utilized as a warning station. to places further to the west and in its immediate vicinity.
Before discussing this question, it will be necessary to glance at. the atmospheric currents of the earth generally. Roughly speaking, the earth can be divided into a series of zones of which the following: is the general summary :
An equatorial zone cf calms. Two trade wind zones. ‘Two semi- tropical zones of calms, and two return wind zones. This is the general geography of the winds of our globe, the only portion which will affect us to-night being the trade and semi-tropical zones of the southern hemisphere, more particularly applying to South Africa.
About the latitude of Cape Town is situated that high pressure-.. belt from which the south-east trade winds blow: this south-east. trade current carries the atmosphere to the equatorial region of calms,. where it rises and flows back again as an upper north-west current, . bearing the name of the upper return trade wind.
The altitude of this current must be very great indeed near the: region of calms, for Smythe when at Teneriffe at a height of 12,000 feet apnove sea level, was still in the region of calms dividing the two
FE
204 A. G. Howard.— The Winter Storms of S. Africa, [ Sept. 28,
currents, and saw cirrus cloud at a great height above him floating from the equator. e
But we in South Africa are very differently situated to what Smythe was at Teneriffe,
The belt of high pressure, which I mentioned before as being about this latitude, is where the upper current reaches the level of the earth, — and as this belt is south of us during the summer, and abreast of us during winter, the return current cannot be very high up. From observations, I have come to the conclusion that tle summer levei of the lower portion of this current is about 3,000 feet above the sea, or slightly higher than the top of the Lion’s Head. Table Mountain and most of the peaks of that range penetrate into this current, which is the cause of the table cloth being spread over these mountains when the south-east wind blows, of which I will speak more anon.
Now the altitude above sea level at which this return current will be reached depends greatly upon the nature of the country. A gently sloping land surface, gradually increasing in altitude as the centre of the country is reached, repeats itself at the lower surface of this current. Thus the height from the land surface at Kimberley to this upper current will be approximately the same as at Port Nolloth which is at the sea level. This can be proved by noticing that the same cyclonic movements which affect the lower stratum of our atmosphere are felt at all the stations over Cape Colony, although some of those stations are over 4,000 feet above the sea level, whereas did the return current flow at an uniform level, it would flow round the Colony like water round a rock, and the atmospheric conditions of high stations would be totally different to those at sea level ; and this, most certainly, is never the case.
But where there is an isolated peak the conditions are different, as in this case there is no gently graduated contour of ground, but an abrupt elevation round which the atmosphere flows; thus the atmos- pheric phenomena may be entirely different at the apex of such a peak to what they are at the base.
Cape Point is such a peak, standing up about 816 feet above sea level, and offering itself as an indicator of coming storms to those who will take the trouble to investigate what its warnings portend.
Before going any further we must come to some decided under- standing as to the physical conditions of a cyclone. What is a cyclone ? A cyclone is a portion of our atmosphere where the winds circle round a definite centre; at this centre the barometer reads lowest, and at
1886. | dllustrating the value of Cape Point asa Warning Station. 205
nee distances outwards, equal barometric readings form a series -of rings round this : the outer ring having the highest reading, and the rest being graduated towards the centre.
The wind does not circle round a cyclone in true circles at all altitudes.
Near the sea level the wind forms the greatest in-going angle with ‘the isobars and this angle gradually decreases, till at an altitude which varies with its position with reference to the cyclone the wind flows parallel to the isobars. Above this point the wind has a gradual out-flowing tendeney, which reaches its maximum at the point where the cyclonic influence ceases.
Below this turning point of the wind’s direction, clouds are very seldom seen, but when anything approaching to a cloud is formed, it ‘takes the appearance of fog. Hence I call this, the fog bearing stratum. The next region of the atmosphere where the winds have a stendency to circle outwards is the stratum of the very lowest clouds. Above this is the great upper current. This current can be divided into two distinct portions ; the lower, which is considerably modified ‘by the direction of the cyclonic centres, and the upper portion which from day to day, month to month, and year to year always flows from ‘some point near north-west, and which is in fact the true compen- sating upper return current of the trade winds.
The former of these is the stratum where the heavy cumulus and -cumulo-stratus cloud is formed, while the latter is the home of the -chrrus cloud.
Nowif the whole solid contents of a cyclone could be rendered visible to one situated externally to it, what would be its general appearance? I will try to make this clear. Suppose we take an invertel cone, perpendicular to the surface of the sea. If the apex ibe immersed in the sea till the circle thus formed round the cone be -equal to the surface area affected by the cyclone, and we then cut off -an ellipse, the one edge of which shall touch the sea and the opposite edge be elevated considerably above it, the solid figure contained between this ellipse and the sea level will be the true form of a cyclone, providing you dish the surface of the ellipse towards the centre.
The next question which itis but natural to ask is—how can you prove this ? A question which I will try to answer.
I shall answer this question by asking another. Why do values ravel from west to east ? hes
We often hear it said that cyclones travel round the sides of areas of
F2
206 A. G. Howard.— The Winter Storms of S. Africa, [ Sept. 28:~
high pressure. But supposing no such high pressure to exist, what then ? And in any case it must be confessed that the barometer is
higher in front of a cyclone than it is nearer the centre, and conse-- quently the low must move to the high. If we assume that a low
cannot flow towards a high, then a cyclone must stand still unless the - high moves forward. But we very often see a high only giving way
when a cyclone forces it to do so, the result being some very stiff blowing, shewing that the high dies very hard. Moreover in a great ~ number of cases the cyclone splits the high into two and forms what is » now commonly called a “col” or neck. Hence the greatest energy must be in the cyclone, and the initial motive power moving it from- west to east must be in itself.
And what is this power? Nothing more nor less than the circulation of winds round the centre.
Let us imagine a cyclone to be situated over the South Atlantic ocean. to the west of us. The winds are blowing round the centre in the same direction that the hands of a clock travel round the dial. But these- winds are of two kinds, one totally different from the other; for whereas: the front wind is an equatorial one, that at the rear is a polar one.
The equatorial wind, or that which blows from the north is a warm: one, which causes the atmosphere to increase considerably in bulk for an equal amount of pressure. Moreover this current is heavily charged. with moisture. But with the polar wind the converse is the case ; for here though the pressure remains the same, the bulk will be much less...
We will now imagine two points at equal distances from the centre,.. one to the east and the other to the west. At both points the barometer reads 30 inches, but there is a marked difference in the atmospheric conditions of the two places, for whereas at the easterly point the warm and rarified air extends to a great height, at the westerly point the air being denser does not extend to such an altitude... Thus the upper surface (so to speak) of the cyclone forms an angle- with the sea level, the line of which if extended to the west would cut the sea at the spot where the cyclonic influence ceases, but if extended to the east would overlap the general surrounding atmosphere and so complete the portion of the cone. It will thus be seen how my figure of the inverted cone is borne out.
From the foregoing it will have been perceived that for equal pressure the air is much more rare con the advance side of the centre
than on the following.
In fact the raresé portion is that in advance of the centre. The-
1886. ] illustrating the value of Cape Point asa Warning Staton. 207
atmospheric pressure is least at the centre, but the air is not the most rarified there.
One of the laws of atmospheric equilibrium is, that dense air
always flows towards that which is most rarified and as the air in the advance half of the cyclone is more rarified than that at the centre, it is easy to see how this centre moves from west to east, and as the whole system of winds travels with the centre, the front will always draw the centre onwards. When a hot stream of water is encountered the cyclone travels along it, because the equatorial air current is more heated there than elsewhere. The Mozambique current is one of this sort, our winter storms generally travelling along it.
But there is another peculiarity as being the result of the oppusite -winds which affect stations of medium height, and isolated like Cape _ Point, which will best be described by an example.
Let us once more return to our cyclone which has been patiently waiting over the South Atlantic Ocean. No, not patiently waiting. for while we have been considering its physical conditions the _advance winds have reached Cape Point.
Simultaneous readings are taken at the various stations, reduced to . 32° and to sea level, and lo! Cape Point reads too high by about a half a tenth of an inch. |
Why is this ? The reading was correct and so was the reduction. ~ Then why this discrepancy ?
If you consider fora moment you will see that such must be the case. Assume the atmosphere greatly rarified, with a sea pressure of 30 inches, then the height of the air column must have been considerably increased, and a greater amount of air must exist above Cape Point than would be the case if the air were more dense, but as the reduction additions to both are the same, providing of course that the tempera- tures are the same, this will make the reduced reading for rarified air higher than it would be if the air were dense. The converse of all - this will be the case on the other side of the cyclone.
Let us now retrogress a little and imagine our cyclone just outside the colony and advancing on to it. Owing to the wedge-shaped form of the advance disturbed portion, isolated peaks will be the first to feel it. Cape Point being such a station we will imagine. ourselves there and follow the sequence of the weather. A low pressure lies _over the centre of the Colony, the wind at Cape Point is consequently south-east. Below, at sea level, it is south.
208 A. G. Howard.— The Winter Storms of S. Africa, | Sept. 28,.
Suddenly a haze is seen to the north-west from which long thread-- like clouds stream out which gradually spread over the whole sky. The general direction of these thread-like clouds is from north-west to south-east. These are what the Rev. Clement Ley calls c7zrro- filum, of which I will speak again.
Following these threads comes a bank of numerous small rounded cirrus clouds, close together, like an immense flock of sheep. These come driving up from the north-west, and as time passes on they grow larger and larger and seem to run one into the other. Towards. the northern horizon they form themselves into a compact white - sheet.
At the back of this mackerel sky, a thin hazy film begins to- shew. Meanwhile the wind calms down at the peak, while it still blows at the sea. Slowly the vane goes round and a north wind springs up. The advance of the wedge is on us. Let us now take our instrumental readings. ‘They are taken, telegraphed to headquarters, . und reduced. The barometer is a half ora quarter of a tenth higher than it should be, while the temperature has risen considerably from what it was at the same time the day before ; the wind too is north, while the general surface current is south and south-east.
Slowly the north wind travels down the sides of the peak till this is the only current observable. The advance of the cyclone is now fairly over the Cape Peninsula, and the usual sequence of falling barometer, changes of wind, &c., follows. When the depression has passed, the wind goes to the west or south-west, often blowing a gale.
Suddenly round goes the vane to south-east again, very often: blowing strong while the south-west wind gradually calms down at the sea level. The storm has passed, as the dense atmosphere, too - heavy to reach Cape Point, testifies ; that peak experiencing the general trade wind circulation of the atmosphere. But should the. vane back to north-west or north, no matter what its direction below, . another disturbance will follow. Hence we see how important a station Cape Point might become in the prediction or fore-casting of weather, more particularly the winter storms.
I cannot pass over this portion of my paper without reference to my sun-spot theory. It will no doubt be fresh in the minds of most here that a paper upon this subject was read before this Society in July last, in which I shewed that a relationship existed between the - positions of the spots on the solar disk and the various storms which.
1886. ] elustrating the value of Cape Point asa Warning Station. 209
visit the Cape. Now if further investigations prove this of any practical value, so that we shall be able to tell for a definite period of time beforehand what nature of a storm to expect at even an approxi- mate date, what an important warning station might not Cape Point be converted into. The sun spots will tell to a day or two when the storm is to be expected, and the observer at Cape Point cou.d telegraph atJeast, and often more than, 24 hours, before its arrival, that it was close at hand.
Having given a general idea of the subject, I now wish to place before you some dry facts and figures. I will confine myself to this year alone. From the first of January to the end of August there were 38 separate cyclones from the north-west, west, or south, purely of the winter type. Taking the state of the barometer on the day of the storm, and on 1, 2 and 3 days before, the following results come out :—
The barometer was high, 11 times 3 days before the storm.
99 “ ff 99 2 99 99 oY) 99 99 | 99 13 99 1 99 99 99 by) and 17 times on the morning of the storm.
Thus we find that during this period, twenty-three storms were foretold by an increase of pressure from one to three days before the storm, while seven had an increase only on the morning of the storm. The total of storms so foretold is thirty. This leaves eight storms un-indicated by increased pressure within three days of their appear- ance.
But increased pressure is not the only thing to be guided by ; increase of temperature is another indication, which I think the following will pretty well demonstrate.
Taking the same time as before we find that the maximum thermometer reading at 8 a.m. was 3 days before the storm 7 times.
a5 ” ” ” 3 455 Les, ” ” » 16° ;; and on the day of the storm 12 __,,
T'wo of the maxima for three days before must be omitted as they were lower than the readings of the days before, but on these days very strong barometer indications are noticeable. |
With reference to the wind changes, one reading a day, and that at the very worst time, is hardly enough to construct anything like tables with.
On several occasions the wind blew from a similar direction on the
210 A. G. Howard.— The Winter Storms of S. Africa, [ Sept. 28,
morning after the change at Cape Point to that at the cther stations. This has been put down as a simultaneous change, while in reality the wind might have changed at Cape Point at a totally different time to the other stations. Twenty-four hours is a long period to pass over without an observation.
Roughly speaking the following are the wind changes :—
On fifteen days the wind changed at Cape Point before it did at the other stations.
On fifteen days the change was simultaneous.
And on three days the change did not take place at Cape Point till after the lower current had changed. ‘These last three I am inclined to consider as due to wrong observations or to temporary whirls. The remaining five instances are very doubtful as the wind was blowing from the north-west all over the Cape Peninsula most of these times ; hence no change seemed to take place.
From the foregoing, the following inference may be drawn.
When there is either an undue increase of pressure or heat at ‘Cape Point, a westerly depression may be looked for, especially if the wind is blowing from the north there, no matter what the ‘direction may be below. |
I have already mentioned that one of the forerunners of a storm is the appearance of a number of thread-like cirrus forms, called by the Rev. Clement Ley, Cirro-filum, but noted down by me long ‘before I ever heard of Ley’s name as thread cirrus.
This cirro-filum is formed at the junction of the two strata of the upper current. The upper stratum of this current always flows from some poiat between west and north-west, but the lower stratum is more or less affected by the cyclonic disturbances, very often travelling from south-west, but more aften travelling from a similar direction to its upper component, although I have noticed it to travel from the south, when any great disturbance was at hand or just passed.
Now if a cyclone is advancing from the west or south-west, the advance edge of the cone will affect the motion of this current, the general direction of which will be more westerly. It will also become more charged with moistnre. ‘This moisture will form into cumulus clouds with perfectly level bases and sharply defined rounded tops. ‘The more moisture is added to these clouds the higher they will ‘become till, impinging on the upper current, their upper portions will be drawn out into long threads by this upper current travelling more quickly.
1886.] illustrating the value of Cape Point asa Warning Station. 211
A great quantity of the electricity contained in these cumulus -clouds will be dissipated into the upper stratum and the particles of water will coalesce and fall as rain. As long as the cloud receives fresh supplies, the cirro-filum will stream off and the rain fall, but -as soon as the supply ceases the rain will also cease and the cirro- filum break up into ordinary cirri. As soon as a fresh supply of -moisture is received, more cirro-filum clouds will be formed, in their ‘turn to break up. It is thus we see such varying banks of cirri roll -over us without a single cloud of medium altitude being seen, those _generating clouds being far below the horizon, but surely advancing towards us. Anexpert if he but knows the point of tne compass ‘from which the threads seem to radiate and the direction they are travelling from, can tell exactly what the directions of both currents vare. ;
Cirro-filum is a sure forerunner of rain. For the last two years Ihave seldom known this. indication to fail. And where rain did not follow at Cape Town it was experienced further up-country.
I intend to introduce as a concluding portion to my paper some ‘descriptions of one or two good typical winter storms which have visited us this year, with an acconnt of the indications of, their approach.
The first of these is a double depression, one which came from the north-west, immediately followed by a very severe ove from the “south-west. The whole disturbance extending from the 11th to the 17th August last.
On the 11th the only indication of a coming depression was the ‘thermometer at Cape Point which at 8 a.m. was 3° higher than on ‘the morning before. The general wind was south. On the 12th although the heat was the same, yet the barometer was ‘09 of an inch ‘too high, shewing a rapid advance. As the general wind was south, -and that at Cape Point south-east, the indications were for a derres- ‘sion from the north or north-west. Next day, the 13th, the heat was 2° higher, while the barometer was ‘07 of an inch too low at “Cape Point; the wind blowing a south-east gale. By the low barometer the first depression had passed, and by the high ther-— -‘mometer another one was not far off. On the 14th neither barometer nor thermometer gave any indications, but the prevailing wind was ‘north-west, while at Cape Point it was north-east ; when the exact -changes took place of course I cannot say, but the indications were ‘for an approaching cyclone from the south-west. On the 15th the
212 A, G, Howard.— The Winter Storms of S. Africa, [Sept. 28,- —
thermometer at Cape Point had risen 2° and the barometer read -O9~ of aninch too high. The general wind was north, being fresh at Cape Point. On the 16th the storm was on us in all its fury. On the 17th this depression was passing away to the east and an anti-- cyelone forming over the Colony.
The first of these two was a dry depression, as far as Cape Town was concerned, no rain falling. The first rain that fell was on the- uight of the 14th in advance of the second depression.
This second storm shewed itself to Cape Town observers by means - of the upper currents while the first one was advancing on us, for~ on the 11th cirro-filum was developed all over the sky radiating from north-west to south-east, remaining there all that day anda part. cf the 12th, after which the sky remained clear till the 14th, when it became overcast. On the 15th at 8a.m.my gauge registered ‘056 of an inch of rain, but on each of the following mornings three-tenths - of an inch was measured, while on the 18th as the storm had passed, only *16 of an inch was gauged. ‘The self-recording anemometer at the Royal Observatory bears out the foregoing description of the- tracks of these two storms, as also do my own daily charts.
The next example I shall give will be that of a storm which I predicted two days before, merely by noticing the direction of the- clouds, in the lower stratum of the upper current.
On the morning of the 2ist of August last, a well-defined depression - of the summer type lay over the Colony. The wind over Cape Town was south. Heavy low damp stratus clouds were driving from the south, while above Table Mountain some heavy cumulo-strati were moving at a moderate speed from the west. What made these clouds - move from the west when the general direction was south ? Nothing could do so but the advance wedge of an approaching cyclonic cone, . and that cyclone must have been to the south. Hence I noted down the prediction that a depression was to the south of us and would strike the Colony in about two days. On the 22nd the barometer had fallen considerably, but this was due to the near approach of the: northern cyclonic centre. The thermometer at Cape Point had risen 7° from the morning before, the wind there being east: at that time, .
(that is 8 a.m.) it was veering to the north. During the afternoon
the barometer at Cape Town reached its mimimum, and a nor-westerly wind sprang up. As the barometer began to rise slight showers fell which continued during the night, the wind freshening. On the: morning of the 23rd the centre of the depression was off East
1886. | iliwstrating the value of Cape Point asa Warning Station. 213
London, the whole Colony to Kimberley and Bloemfontein being affected by it. Fresh north-west and west winds blew all over the Colony.
The rainfall in Cape Town was moderately heavy, being °36 of an inch in my gauge on the morning of the 24th. On the whole of the 23rd, in fact, the weather was very stormy and squally, especially during the evening when some very heavy squalls were experienced. On the morning of the 22nd the Cape Point barometer read ‘02 of an inch higher than it should, which indicated another depression and sure enough during the day a small secondary passed.
One peculiarity of the wind at the Royal Observatory as self- recorded is that from 7 a.m. till midnight on the 23rd the wind although generally calm as registered by the mileage trace, yet passed in a series of squalls which kept on continually altering the direction of the vane from north-west to west, back to north-west then to south-west and south-east, back through west to north-west and . repeating itself over and over again many times each hour.
It is in cases like these that the anemometer trace fails to indicate » the intensity of individual gusts. One gust at half-past-eleven is visible on the trace as a very slight horizontal line. The speed at. which the cups must have revolved for this short time must have been . inconceivable. )
There are a few more of these faint horizontal marks, but the one I have mentioned is the most conspicuous.
I could go on multiplying cases if I liked, where storm after storm - passed, but there would be sucha sameness about each one that it would become very monotonous, as the general sequences are the same, . the only variation being due to the directions they come from, and the tracks of the centres. If they come from the north-west they are: preceded by south-east winds which suddenly go round to the- north-west as the centres pass; but if they come from the south-- west, they are preceded by north-west winds, which chop round to - the west as the centres pass.
These latter are the ones which bring the most rain to this end of © the Colony. The reason of this is that the left-hand half of the. cyclone is the wet half, so that if a storm comes from the north-west and passes us to the north-east, we are the whole time in the dry half of the cyclone.
At the beginning of this paper I mentioned that the Table Cloth on Table Mountain was due to the presence of the lower stratum of the -
“D4 A. G. Howard.— The Winter Storms of S. Africa, [Sept. 28,
return equatorial current ata level of 3,000 feet above the sea. I promised to speak more on this subject and I may as well introduce it here before concluding. You will remember I said that when the -contour of a country was gradual the atmospheric currents did not flow round but up it. It is thus with the backbone of the Cape Peninsula. From Cape Point the slope is gradual to the high table land behind Simon’s Town. From there it is comparatively level ‘(with the exception of the slight depression at Noord-Hoek) right on ‘to the Constantia and Muizenberg range. From Hout Bay the slope is gradual up to the back uf Table Mountain and the Twelve Apostles range.
Thus when a south wind blows round this end of the Cape Colony, the wind instead of flowing round the Cape Peninsula is carried up the sloping backbone before mentioned and impinges into the lower portion of the return current.
Now as this return current is warm and charged with moisture, the -cold dry southerly current rushing into it condenses the moisture into the heavy cumulo-stratus cloud which we commonly called the Table
Cloth. As the wind whirls over the cliffs of Table Mountain it once more
reaches the lower and colder stratum ; the particles of cloud mean- while having a propulsive and upward tendency are soon dissipated, the general appearance being that of a cloud constantly being formed and as constantly disappearing, a phenomenon familiar to us all. This is briefly the cause of the south-east cloud. When the high pressure belt is further to the south and the return current exists above Table Mountain, or else when the general -currents are southerly, no cloud can form, We have then what is -commonly called a blind south-easter. A black south-easter is not a south-caster at all but a south-wester, and is generally the following wind of a winter depression. There is still one investigation which would be very beneficial to che study of the tracks of winter storms, and that is, the annual position of the South Atlantic anticyclone. The position of this has 4 great influence on the direction from which the storms come to ‘the Colony, and as this direction affects the rainfall, it will be seen how important it would be to be able to tell exactly for a year or two “in advance, from which direction the storms would come upon us. J have no doubt that when this is investigated it will be found to have a cycle agreeing with the sun spot period of about eleven years.
1886.]| illustrating the value of Cape Point asa Warning Station. 215.
Ido hope that someome will be stirred up with an ambition to solve this problem, which is of such importance to a colony depending for its prosperity on its rainfall. - Paper after paper bas been read on the subject of South African Meteorology, and still no one seems stirred with any desire to further its study, except a few who have: to struggle alone and overcome difficulties greater than most people- imagine exist, for I do not believe there is a more disheartening study in the world than that of Meteorology, and especially that of. South Africa.
Apotpepu G. Howarp. September, 1886,
°216 A. G. Howard.— The Winter Storms of S. Africa, | Sept. 28,
CAPE POINT.
Height of Thermometer, one, two and three days before a winter Storm, and on the morning of the Storm.
Days before Storm.
: No. of Storm.
] 63 63 2 66 68 3 65 65 4 64 65 5 63 62 6 60 64 i 58 59 | 5 60 an a 9 60 62 |
22 57 ol 23 do o4 24 5d ol 25 62 56 26 49 50
1886.] illustrating the value of Cape Point as a Warning Station. 217
No. of Storm.
CAPE POINT.
Days on which the wind changed (x) at Cape Point and (0) generally over the Cape Peninsula, one, two and three days before the storm, and on the morning of the storm. As only one reading is taken a day (8 a.m.) it is hard to tell when the wind really changes, so that this can only be regarded as an approximation.
Days before Storm.
2 i stale Q) Xe 2: al x <rO Bae xX O
Y
xX O reve O
x ie >)
ast x Undiecided
x O ae a 56) 6) Xe ae x all the | time De Obs
C.P. Cihanged 4 .| all the | time x No Ch
xO ae | x O
No Change x oO a
Day of Storm.
hel
befjore
OW
| No change below |
218
winter storm, and on the morning of a storm.
ee
No. of Storm.
A. G. Howard.—The Winter Storms, &c.
CAPE POINT.
Differences between barometer readings reduced to sea level and as. indicated by the isobars, on one, two and three days before a
Days before Storm.
OMm~AIDNK-WW
Totals
ee
eae
wo
— 07
lti+t. S6559°
C2 bo Ww Or bo
‘Sees lee ° ae: oo Ww
+°03
_ Morning of | Storm.
3 + 04 =O == 705 = {2 aE Oz +°05 |Norecord aL ol aS | + -O-4 a),
ee 5 (5) == "00 a O2 | == (5) EF, |
1 o(0/3) STEEN |
i. a= OS SEO ae
ms | =e 0) + -02 | od id. Shel
orn +°06 |
TEE Oa)
253 08) +:06 + -O4 ee & 03 wae +:09 LOE + 09 bys
ee +> a(t. es (8-4
3 ar |
4 it
[ Sept. 28,.
Too high
Too low
eee Eee errr e rere ee —Eoo—_ -
alse et Ail
CAPE POINT.
Diagrams shewing (1) differences of Barometer Readings, as reduced te sea level, from what they are indicated by the Isobars; and (2) the Readings of the Thermometer, on 1, 2, 3 days before and on the day of the Storm.
a | aS SS SS BAROMETER THERMOMETER BAROMETER THERMOMETER Days ae tee Days | Days a[etfe sTeltfelslet]
/ = La oy / ~
| 4+ WA FEE 8S MU WwW
ag WU trem ep LITT P/U | Ses mar mabe SS MM wu 2 Wi Wii Vii S ll |!
= aire io a | Libis
aes
\
nn
aw
ITLL ly ne: WW f O ees LIL toe
pee Ht FMW Ree | Pa ——-}~
MMU Wh WW
Wy ~ —— L— aa
34 Wu Mie
RGN 2EEEE (ole WwW F aes N
| MS her oe n — |
Ye me eee
WS MW. Win DMM: | 35 -— | ll "is Soi are | 16 om: 36|__|_ dll 2 ae 17 [hmm 3 ra | 3 aa |
Scales. Barometer )6/2 = Moi? Thermometer i" = 102
ON VAN WYK’S VLEY RESERVOIR. By J. E. Macnee tian, C.E., [Late Restpent ENGINEER ON Van Wryx’s VLEY Works. |
[READ 27th OCTOBER, 1886].
BrErore proceeding with the main subject of this paper, it may not be out of place to make a few remarks on Boer dams in general, showing that more care should be taken in the selection of their sites, and in their mode of construction.
Many of these sites are far from being good ones, some having such small catchment areas that they never half fill, and their con- structors have the mortification of seeing a huge bank, with little water, besides being put to much unnecessary expenditure ; others again are constructed on a porous stratum through which the water percolates away rapidly, reudering the dam almost useless for irri-. gation purposes and only giving water for stock for a comparatively short time. These faults can be avoided by making a proper survey with levels, and by sinking pits along the proposed line of bank, to ascertain the nature of the strata forming the foundation.
A common fault in many of these dams, is that the inside or water: slope is made too steep, causing the pitching to get loose and fall out in many places, thus giving free access to the wash of the water, and to the ravages of crabs. ‘This if not noticed and repaired at once, may often cause the entire destruction of the bank, and the loss of a whole season’s water and crops.
More care should be taken to incorporate the bank with the ground on which it is to be made. This is done by removing all loose stones,. sand and bushes, and picking the ground to a depth of eight inches: or so, before beginning the first layer of the bank.
The general method adopted amongst the farmers in the construction: of their dams is to convey the ground to the site of the bank, in earts or scrapers, allowing it to assume its natural slope, or angie of repose. This for most kinds of ground is quite insufficient, when exposed to the action of rain or standing water. A farmer once.
G
220 J. E. Macnellan, C.E.—On [Oct. 26,
called on me and said he had just entered into a contract for the construction of a reservoir bank on his property for a certain sum, and now wished to know how much earthwork would be required to finish the work, insisting, in spite of my remonstrances, on only giving such slopes as the material would stand at when first tipped. The slopes were not to be pitched, owing to the scarcity of stones. Tt will scarcely be a matter of surprise, if this dam, so constructed, should be washed away by the first heavy rain.
Another fault in many of these dams is that too little attention is paid to their overflows, and this is a very serious one, for the existence of the bank depends almost always on a proper provision being made to carry off the surplus water after the dam is full. If this point is neglected the water will rise till it reaches the crest of the dam, when it then only becomes a question of time for it to share the fate of many others whose safety valves have been omitted or made too small.
It is scarcely a matter of wonder to hear of so many dams having given way after a heavy rainfall, when they are made in this haphazard style by men who have little knowledge how to construct a bank able to withstand the denudation caused by alternate filling and emptying as well as by the insidious percolation of standing water.
Outlets should, where practicable, be placed some distance from the bank, a natural ‘nek’ being best, but where such is not to be found, the overflow may be formed by making a cutting, or by leaving a sufficient — opening as the end of the bank. In the event of the latter plan being adopted, the bottom, and side next the embankment, should be- protected from scour by substantial stone pitching. A training wall or bank must also be made to lead the water clear away from the outside slope, and protected with stones or bushes where necessary.
Front slopes should always be pitched, if there are suitable stones to be procured in the neighbourhood, to prevent damage from. burrow- ing of crabs and trampling of cattle.
From the foregoing remarks it is not to be understood that all the dams in the country are badly made, far from it, for there are many
excellent ones, which have stood firm for years, proving a source of wealth to their owners, and showing them that substantial work pays the extra outlay in the long run. But althou h some grave errors have been pointed out in the general construction of dams, the farmers are not altogether to be blamed, for they have to contend with many difficulties and troubles which most people in the large towns know little or nothing of. What they have chiefly to struggle against are
1886. | Van Wyk'’s Vlei Reservoir. 221
the terrible droughts which are so frequent in the back country, and which sometimes last for years, reducing well-to-do farmers to a state of bankruptcy. Often and often are they obliged to shut up their houses, collect. what stock is left to them, and trek with their wives and families to distant parts of the country in search of veldt and water, not knowing when they again can return to their homes.
How then can it be expected that people, living in this hand-to- mouth manner, are able to pay for expensive surveys and construct proper and substantial works ? It is entirely out of their power, and the most they can do is to construct, with what labour they have -about the farm, a dam to hold as much water as possible, adding to it as time and opportunity permit. Often a heavy storm destroys all their labour, before the work is properly finished.
An Irrigation Act was passed a few years ago, authorising the loan -of money, on easy terms, to enable farmers to construct dams, and other works, for irrigation purposes, and many took advantage of it, but a great deal has yet to be done to give effectual assistance to the poorer class of farmers. |
The Dutch farmer, as a rule, adheres tenaciously to the methods used by his forefathers, in dam making and farming, but many are now appreciating the use of such scientific appliances as siphons, turbines, and pulsometer or other pumps for irrigation.
When he sees lands which are regularly irrigated, thriving and producing all kinds of crops and grain, whilst his own are dried and parched with drought, he naturally wishes to possess the like, and Ihave no doubt that, in course of time, large tracts of fine land which now only afford a precarious support to a few sheep and goats ‘will be made to produce an abundant supply of grain and other produce, the most of which, at the present time, has to be imported -at a great cost.
Those who have travelled much in the Karroo cannot have failed to observe that wherever a farmer has been able to irrigate, the -luxuriant vegetation appears. to the eye, wearied by miles and miles -of dry and stunted bushes and with nothing to vary the monotonous -appearance of the country, to be a veritable oasis in the desert. | There is no reason why these patches of cultivation should not be ‘more numerous and extensive than they are at present, for on most — farms there are sites more or less favourable for storing ‘the rain which falls so seldom, and which should in consequence be preserved
48 much as possible, to meet the demands in time of drought. Gi
292 J. E. Macnellan, C_.E.—On [ Oct. 26.
Many of these sites are on Government lands, and the one at Van Wyk’s Vley is one of the most extensive and favourable yet brought to the notice of the public. A short description will now be given: of the manner in which the works at that place were carried out... The designs were prepared by Mr. John G. Gamble, the Hydraulic— Engineer to the Colony. The contract for the work was signed on the 28th October, 1882, and the first ground was broken on the Ist. December following, the author having been appointed resident engineer.
Before the contract was given out for tender, trial pits were sunk. along the centre line of the bank in order to find, if possible, an impermeable stratum on which to found the puddle core. These’ were put down by the foreman (R. Taylor) who came out from England to undertake borings. He found on the one side of the kolk or river a stratum of hard rock, varying from 8 feet to17 feet below the surface of the ground. Close to the east side of the river.no roek could be found, and it was supposed to have been cut off in or’ near to the other side, this was afterwards, as the work proceeded, found to be correct. Instead of rock, a succession of shales was found, overlaid on the koppies, which formed the’ abutments of the bank, by beds of a very hard rock, which are much split up but cemented together by deposits of lime. A bore hole was- put down on the east side by Taylor to a depth of 50 feet but he did not get through the shale. These shales for a depth of 10 or 12 feet were of a very friable and porous nature, and it was found: necessary to excavate to a considerable depth to get a good foundation...
The contractors (Messrs. Gillet & Perez) then began the work by clearing the ground of all stones, sand and bushes, and Ly loosening it with picks and ploughs toa depth of 8 inches. On this prepared found-- ation the embankment was raised. Simultaneously with the starting of the bank, a trench was excavated, extending the entire length of the bank, and down to the rock where rock could be found. This trench was 8 feet wide at the bottom, the sides having a batter to meet the puddle core of the bank, at the natural surface of the ground. It was then filled in with puddled clay, made as will afterwards be described. The puddle core or wall, placed in the centre of the bank was carried up to within 3 feet of the top, where it reached its- minimum width of 4 feet, its sides having a batter of | in 5,
Great difference of opinion exists amongst engineers as to the proper position of puddle in earthen dams. Some advocate the
“1886. | Van Wyk's Vlei Reservoir. 228
placing of a layer on the face of the inner slope, immediately below -the pitching. This method can certainly not do much harm, but it is doubtful if it does much good, at all events for banks of any great peight, for in this hot climate, when the water in the reservoir is low >the paddle is liable to crack and this materially affects its usefulness. Another plan is to construct a puddle wall in the centre of the bank, - continuing it down till the rock or an impermeable strata is reached.
This was the method adopted here. The use of this puddle wall is to ‘prevent as far as possible a leakage of water through the bank, which ‘ might prove dangerous to its safety, and which is generally caused by
bad workmanship, use of permeable material or the burrowing of crabs and mice. |
Most people know what the meaning of puddle is, but for the benefit of those who do not, the following description may be useful. The material used is clay, freed from roots, stones and dirt. When made by hand, it is mixed with water, cut up and worked with spades, ~well tramped and kneaded until it is of the consistency of putty. It was made in this manner for Van Wyk’s Vley reservoir. If the clay is pure, as much sand may be mixed with it as is consistent with its holding water, for if there be too little sand it is liable to crack in dry weather. This would more particularly apply to puddle laid on - the slope than to that in the centre of a bank. If too much sand is used the puddle will become porous and therefore useless for the purpose for which it is required.
_ After the puddle was made, it was brought on to the bank in carts drawn by mules, which were found to be much better than bullocks or - donkeys for this part of the work, and then spread in horizontal layers about 9 inches thick, well beaten down to the preceding layer, which was first thoroughly wetted, so that the layers would _ amalgamate together.
Hach layer as far as possible was carried the entire length of the bank at once, but where this could not be done steps, of a thickness of ‘. one layer, were left so that a proper junction could easily be made.
The forming of the bank and the puddle core were carried on simultaneously in the following manner. When a layer of puddle was finished, it was allowed to dry till it was sufficiently stiff to bear the pressure of the earth placed alongside it. This was‘brought on in mule carts, while the bullock and donkey carts were worked towards the outside of the bank. This way of working was necessary because “bullocks and donkeys cannot be guided so well as mules or horses, and
294 J. E. Maenellan, C.E.—On [Oct. 26,.
when once on to the puddle, they sank for several feet, and it was then a matter of great difficulty and loss of time to extricate them.
The earthwork of the embankment was made in layers of about 1 foot thick and well beaten down with heavy rammers before the next was laid on it. The best material was selected and placed to form the water side of the bank, extending back to the puddle core. No stones or shale were allowed on this part of the work, but could be placed behind the core of the bank, due care being taken that there was sufficient fine material to make the mass solid.
The embankment was formed in concave layers, that is to say, the bank was kept from 2 to 3 feet higher on the outside, sloping downwards to the puddle core. This method makes the bank more solid and tends to prevent slips, and should always be adopted, the extra trouble being more than compensated for by having a stronger bank, with the same material.
The contractor, not being a man to lose time or waste opportunities, took advantage of moon-light nights to bring on the earthwork. This was entirely confined to men who owned one or two spans of bullocks,. one span working during the day, and the other at night. He paid for the work done at so much per load, brought on to the bank, a certain number of loads being fixed as a minimum, for men had to be employed in spreading and ramming the ground. In order to keep tally of the number of loads, each driver received a ticket from the man in charge when he tipped his load, and when the number of tickets reached ten, they were exchanged for another representing ten, and in the same way when these reached ten, they were given up for one worth 100. These tickets were presented at the contrac- tor’s office at the end of the week and paid for according to the rate per load. This system worked well and a large amount of work was. thus done. When the bank had been raised to a convenient height levelled pegs were put in, and the front and back slopes trimmed to- their respective batters of 3 to 1 and 2 to 1. The front slope was then covered to a thickness of 18 inches, with a layer of stones and small. boulders, on which was placed the pitching of stones 12 inches thick..
To guide the men in laying the pitching properly, pegs were placed at intervals of about 80 feet along the bank, and about 20 feet apart down the slope, on which stout cords were stretched, thus giving the proper level and slope. When the pitching was finished a layer of small stones or gravel was spread over it and raked about to fill in the:
interstices between the stones.
1886. | Van Wyk’s Vlei Reservoir. 225
As all made-banks are liable to settle down more or less, the top as finished was kept higher than the normal level, by one half-inch for every foot of vertical height.
A coating of 3 inches of gravel was spread over the top of the bank to protect it from rain, and the trampling of cattle and sheep ; and along the edge of the inside slope a dry stone wall 2 feet wide by 2 feet high was built as a protection from spray, &c.
The water is led from the reservoir to the main furrow, by means .of twoiron pipes, one of 20 inches in diameter and the other 12 inches. These pipes pass through a culvert made of concrete 4 feet wide by 6 feet high, which is built in the solid ground in the kopje which forms the east abutment of the embankment. At the reservoir end of the culvert is built a stone tower, in cement mortar, 33 feet high, with an external diameter at the base of 13 feet, and at the top 10 feet ; the internal diameter being 5 feet. This tower is for the purpose of working the different valves, of which there are five in all, each of the two pipes being pro vided with two, a shuttle valve on the outside, and an ordinary one in the inside of the tower.
The fifth valve is a 6-inch one to be used for any water which may collect in the tower. Access is obtained to the top and inside of the tower, for working the valves, and for making repairs, by means of iron steps built into the masonry.
The top of the tower is covered with cast-iron plates, resting on the walls and on the channel irons, which support the pillars through which the valve rods pass.
The 20-inch pipe passes through the base of the tower, its centre being nearly 26 feet below the highest water level. It is then laid on the floor of the culvert, extending as far as the plug wall, or as far as the puddle core of the embankment.
The 12-inch pipe draws water from the reservoir at a point 13} feet below the highest water level, passes down through the tower into the culvert, where it rests on brackets supported on short iron columns, at a height of 3} feet above the floor.
At intervals of 9 feet along the top of the culvert, masonry rings, set in cement mortar, 2 feet wide and 1 foot thick, were built to i arrest as much as possible any percolation of water, and so that the earthwork and puddle of the bank should join firmly with the | masonry. ‘The filling in of the space between the top of the arch and the surface of the ground was carefully done. A layer of ground was first putin and thoroughly soaked with water, well trampled and
226 J. E. Macnellan, CLE.—On [ Oct. 26,
rammed till all the interstices between the culvert and the excavation above the springing of the arch were filled in. After the pipes and valves were properly fixed, the portion of the culvert from the tower for a distance of 75 feet was built in solid, the material used being plincipally concrete with a little masonry. This plug was made longer than is usual, on account of the shaly nature of the ground below the culvert. The depth ofthis shale, as I before mentioned is unknown, a 50-feet bore having failed to pierce it. It is not unlikely that the water from the reservoir will soak through this shale and issue out at some point or points beyond the bank.
Advantage has been taken of a nek some distance from the bank to construct the overflow. The ground was excavated and levelled for a width of 150 feet, which is calculated to be amply sufficient to carry off the surplus water. :
When the water in the dam is on a level with the bottom of the 20-inch pipe, that is, is empty, the area of what remains in the kolk is 34 acres. This can only be used for watering stock. The extent of land covered by water when the dam is 4 feet deep at the tower, is 500 acres, and at present (March 1886), with a depth at tower of 6} feet, it is at least 800 acres.*
Beacons have been erected at suitable poiats outside the dam so that its area can be easily and expeditiously measured at different levels. This will subsequently be of great value, as a close approxi- mation can be made as to the amount of water available for irrigation and other purposes.
Careful and regular measurements have been taken of the depths of the water in the dam to find out, as far as possible, the rate of evaporation and soakage.
No water at all was taken from the dam in 1884, so the amount as shown in the annexed table represents exactly what was lost by evaporation and soakage during that period,
Irrigation was first commenced in July 1885, and has been con- tinued up to the present time.
The amount of land under cultivation is about 25 acres, but the water used for this patch bears a very small proportion to that lost by evaporation. Ina whole day’s leading, no appreciable difference in level of reservoir could be detected, the loss during the year 1885 may be considered as almost entirely from evaporation and percolation. The observations of the two years can thus be compared, from which
* No chance to measure yet.
1886. ] Van Wyk’s Vlei Reservoir. 227
will be seen that the holding properties of the dam have much improved. In 1884 with a mean maximum temperature of 78°'8, the loss of water for the whole year was 89°6 inches, whilst in 1885 with _a mean temperature of 80°1, or a daily increase of 1°3 the loss of ‘water was 76'1 inches, or less by 134 inches than that of the previous
year. This is satisfactory, as it shows that, so far, percolation has decreased.
There is a rain gauge fixed a few bhnndred yards from the embank- -ment, but it is necessary for estimating the amount of water that - might be expected from a certain fall, to have stations fixed at several points of the drainage area of the dam. Such other stations have been established recently. The rains being very partial, a storm may occur only a few miles away and bring a considerable quantity of water to the dam, while the gauge at the bank registers nothing. Judging from the observations that have already been taken here, one half-inch of rain practically gives no increase to the dam, unless it immediately follows a previous fall. (See annexed report on the rainfall, 18th May 1885.)
In conclusion may be given a short description of the distributing -channel or furrow. Mr. Alston’s tender being accepted, operations for this part of the work were commenced on the lst of January 1835, and finished within the specified time of five months.
The dimensions of this channel are 3-feet wide at the bottom, 1l-feet wide at the maximum water level and 2-feet deep, giving a sectional water area of 14-square feet.
Banks were made on either side 2-feet wide on the top with a mininimum height of 3-feet above the bottom of the furrow.
The slopes were 2 to 1 below, and 14 to 1 above the highest water level. Wooden forms were constructed to the finished section of the channel as a guide to the workmen.
The gradients of the channel are at the rate of 3-feet per mile for the first half mile, 2-feet per mile for the next two miles, the ‘remaining length being at the rate of 1 foot 9 inches per mile.
The bottom and sides for the first quarter of a mile are pitched \with stones, but the remaining part has no such protection, and up to ‘the present time has stood well, tke water flowing regularly, without
‘scour. Openings, protected by pitching, have been left in the banks © -at suitable places, to carry off flood water ; these will probably require some repairs after storms. |
The branch main road to Kenhardt, via Van Wyk’s Vley, is carried
228 J. E. Macnellan, C.E.—On Van Wyk’s Vlei Reservoir. [ Oct. 26,.
across the channel by means of a bridge, with stone abutments and’ wooden beams, the main road crosses by means of a drift pitched with large stones, and well gravelled.
The length of the channel is a little over four-and-a-half miles, the surveyed plots beginning at a distance of about two miles from the reservoir. The land along the first portion of the furrow is at present reserved by Government, for tree planting &c., it being too narrow to be given out as corn lands.
A variety of trees and slips were planted here last July and August and most of them are thriving. Some poplar slips have now attained (in nine months) a height of more than 5-feet, showing that they at least grow exceedingly well. Mr. Alston has charge of the tree planting here, and will test what trees are most suitable to this part of the country, and the result, being a matter of great public impor-- tance, will be looked forward to with interest both by those who are lovers of nature and by those who look to the financial side of the-
question.
THE “!NARAS.” ACANTHOSIOYOS HORRIDA HOOK.
By R. Martotu, Pu.D., M.A.
[READ OCTOBER 27TH, 1886.]
Amonest the large number of curious plants which Southern Africa has produced are two most remarkable ones, which occur in the neighbourhood of Walfish Bay. The one, Welwitschia mirabilis, the ‘*Tumboa”’ of the natives, was discovered some twenty-five years ago by Welwitsch. The other plant, the first specimens of which were brought to Europe by the same traveller, is our present subject, the Naras, or more correctly pronounced ! Naras,* Acanthosioyos horrida. Welwitsch found both plants much more north than Walfish Bay, a little south of Mossamedes, and realizing at once the scientific value of his discovery with respect to the first plant,. he took care to collect a good number of complete specimens.
With the Naras, however, he must have been less lucky in his findings. There are only incomplete specimens in his collections and the description of the plant, published in Oliver’s “Flora of Central Africa” does therefore not mention some important character- istics of it. I shall spare you, of course, the botanical diagnosis of the plant, and deal here only with its external habit and its value to the natives in the neighbourhood of Walfish Bay.t
Besides a few spots near to the Capes Cross and Frio, the Naras: grows almost exclusively in the angle formed by the lower Kuisib- and the coast. There is little doubt that this river formerly entered the sea at Sandwich harbour, but the advancing sand dunes barred its way and compelled its waters to flow more northward, whenever it happened that flowing water came down so far; an event some- times unknown for more than twenty-five years. Although there is very rarely open water in the lower course of the river, its sandy bed contains always the precious liquid some depth under the surface,. and a portion of this water forces its way underneath the sand dunes
* The ! indjcates the palatal click of the Namaqua language.
+ For fuller information see the author’s monograph of the plant in Lngler, Botanische Jahrbiicher, Vol. IX.
223.0) Dr. R. Marloth, Ph.D.. M.A.—The - Ost. 27,
down to the coast. This is the source of the splendid water found -elose to the shore at Sandwich Harbour and then again at Sandfontein, -at the back cf Walfish Bay, and this subterranean water enables also our plant to grow on the sand hills between these two places.
No other vegetation can exist on this moving sand under a tropical sun and a continuous drought, for rain is almost as rare there as here for instance an earthquake. The root of the Naras descends deep into the sand until it reaches the hidden moisture. It has sometimes a length of forty feet. A French missionary, Rev. Duparquet, who calls Damaraland Western Caffraria, and whose statements are published by Monsieur Naudin, and taken thence into a recent number of the ‘“‘ Gardener’s Chronicle,” tells us that the root is occasionally about 350 feet long and descends to unknown depth. Well, the Naras is a curious plant, but a root of 350 feet length and an unknown depth into the bargain is rather a strain on a naturalist’s imagination.
The Naras is a cucurbitaceous plant. It belongs therefore to a family, some members of which are very useful to man. I need mention only the pumpkin, cucumber, watermelon and rolaquint. But its appearance is totally different from all its relatives.
The root puts forth successively several shoots of a finger’s thick- ness. But no leaves are to be seen thereon. The shoots branch out several times and bear two conical spines at each node. As the very slender branches are much entangled and interwoven they cover the sand dunes like a hedge and it is very unpleasant to pass through | such a hedge on account of these sharp pointed thorns.
The prevailing wind on this part of the coast being a southerly one, the sand dunes change almost daily their form and bury conse- quently very often the Naras bushes; but that does not matter. The more the sand tries to cover it, the longer become its shoots—and always provided that the root has reached the moist region of the
sand—the plant remains victorious and always afresh overtops the sand.
It is a most striking sight, these green bushes on the top of the -ever-moving hills, whilst the sand around them is bare and nude, and
it has been a puzzle to a good many people why this plant almost always prefers the exposed tops to the valleys between. The truth is the plant does not favour at all these spots, but being attacked by the sand it struggles for existence and whilst the sand is heaped around it and on it, it grows longer and longer, and it is strong enough to succeed in a struggle which would overwhelm any other plant.
1886. ] “!Naras.” <Acanthosioyos Horrida Hook. 231
It is wonderfully adapted to such an existence. All the kindred
plants are conspicuous by their largely developed leaves, but this member of the family does not form any leaves at all, because it would be impossible for the plant to supply the necessary quantity of water: for their maintenance and the leaves would be quickly seorched. The- evergreen shoots and twigs do the work of the leaves, the respiration and assimilation. But even these require water for their life. The plant must therefore possess a well-arranged system of water-pipes. .The piece of root, which you see here, is as light as cork, almost spongy. The reason is, that it contains numerous and ample vessels, visible to the naked eye. In this dry piece, these vessels are filled with air, but in the living plant they contain water, which is carried along them from the rootlets deep down below to the green parts of the plant on the tops of the hill.
There are also some excellent arrangements in the anatomical con-- struction of the younger parts, whereby the green tissue is protected against the scorching effects of the heat, but it would lead us too far to enter here into this question.*
The flowering season begins with the summer, the first fruits ripening about Christmas. As the plant is dioecious, not all the bushes bear fruit, on the contrary, the female plants seemed to be in minority. The fruit attains the size of a child’s head ; it is green even when ripe; is armed with sharp knobs and becomes soft on ripening. ‘The natives use a bone-knife, made from the rib of an ox for opening the fruit, because the juice of it would bring about an inflammation of the fingers. Differing from other cucurbitaceous. fruits, its six parts are easily separable from each other like the sections of an orange. ‘The colour is that of a carrot, flavour and taste something like spanspeck, but rather sharp.
With the ripening of the Naras pleasure and joy enter the hearts of the natives who live between the sand dunes. They are a tribe of Hottentots called “ Topnars.”” ‘Their existence in such a desert may appear to us‘a very wretched life, but to them it is then really a paradise, for in the commencement of the Naras season they do nothing but pluck the fruit, lie on the sand all the day long and devour as much of the “lekker kost” as their stomachs will hold. Kvening and night are spent in singing and dancing, and in the morning begins again the hard work of the previous day.
As the fruits become more numerous, those of the nation who are
* See figures in above monograph.
232 Dr, R. Marloth, Ph.D., M.A.— The [ Oct. 27,
wise begin to make preserves. They put the pulp ina pot and boil it down toa thick pap, pouring it then through a sieve of their own invention, which retains all the seeds, whilst the pap hardens on the sand to a flat cake. Both these products, the seeds as well as the inspissated pulp, are put aside for later times, when no more fresh fruits are to be met with. They form the principal food of these people, who eat the seeds as they are and boil the pulp up simply with water, obtaining thus.a very nutritious soup. The seeds are also regularly brought to the Cape Town market, known here as butterpits. They contain much oil, whilst the pulp is rich in albuminous matter and sugar.
The most interesting property of the fresh fruit is its effect on milk. During my travels I heard it mentioned from different natives that the aroma of the Naras acts on milk like rennet. They stated invariably, that milk kept for a few hours in a room, where a Naras lies, will turn on being boiled. When I came back to Walfish Bay, T inquired there into this question. All the Europeans confirmed the statements of the natives. One lady mentioned for a proof thereof, that she placed a jug with milk in a cupboard where a Naras was and found that the milk turned on being heated a few hours after- wards. On my question, whether she had kept a portion of the same milk somewhere else and tried it for comparison after the same time, she answered, no; admitting then, that her one-sided experi- ment was not conclusive.
At my return to the bay the Naras season had already passed several months ago, but as it was of the utmost interest to me to ascertain how much of these strange statements was true, I asked some men to look out for afew fruits. On hearing that IJ wanted the Naras only for experimenting with them on milk, they laughed apparently at my ignorance in a matter which was known to every child in