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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, _

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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.

ag Fears paw Re a

va feet ity es wd fu: aod

rhe Bho®. a toa ae

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

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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 the
country, but by the promise of some coffee and tobacco I induced a
small party of men to search the whole area for full grown Naras.
They brought me three, but they were hard. Yet, by nursing them
properly, that means to say, by exposing them to the sun at day-time
and taking them into the room before the evening mist came on, I
managed to ripen them in a week’s time. Fortunately I had a spirit-
lamp and some test-tubes with me, which enabled me to make a series
-of experiments.

I think it unneccessary to enter here into the details of these
experiments and I shall mention only the results of them.

1886. ] “/Naras.” Acanthosioyos Horrida Hook. 233

The juice of the Naras contains really a principle which acts on
milk like the rennet of the calf.

This “ vegetable rennet,” as I may call it, is not volatile. It is
therefore not the aroma of the Naras which spoils the milk at Walfish
Bay, but the negligence of the milk-boys, who eat Naras all the day
long, being certainly not over-cleanly and careful with their hands and
milk-pails. As there is no grass near to the bay, the cows are kept at
a place about seven miles off. The boys bring the milk from there
every morning, and it is a general belief that milk, brought by a boy
‘who carried at the same time a Naras, even in his bag only, will
turn.

My experiments showed that there is no such active principle in
the aroma of the fruit, but as the coagulating power of the Naras-juice
is nearly 1 in 2,000, that means to say, that one drop of it is sufficient
-to coagulate three ounces of milk, or a tea-spoonful for one gallon and
half, we can well understand how easily the peuce of a Walfish Bay
kitchen is endangered during the Naras season.

Concluding my little paper I may be allowed to draw your attention
to the two most remarkable facts connected with this plant.

The first is the mere existence of it under such trying circumstances.
And it exists not only itself on these moving sand-hills, but it renders
there possible the existence of a whole tribe of natives, whom it
furnishes with food and drink.

The second fact is the renewed proof that the man of science can
never rely upon the statements of others, for although in the country
of the Naras nobody doubts the fabulous quality of its aroma, this
‘universal belief is inconsistent with the result of exact experiments.

THE ORBIT OF COMET 1886 (FINLAY).
By Wi He Pinway, MCAS Eo. Acs:

[READ 24TH NOVEMBER, 1886. ]

I discovered this comet on the evening of September 26. After
computing several parabolic orbits which failed to satisfy further
observations, I calculated the following elliptic elements from my
observations on September 29, October 10 and October 21.

To ENO: 24-6056 Greenwich mean time.
x 10° 46’ 18") Eeliptic and mean Equinon
Q d3 38 14 1886°0.
Pete OT, 0

log a 0°485900

loge 9°835091

pp ~~ 662""456
Period 1956 days.

It is not improbable that the Comet is identical with the first of.
1844, the “lost de-Vico.”

THE STORMS OF SOUTH AFRICA.

By A. G. Howarp.
[READ 4TH MAY, 1887.]

INTRODUCTION.

~ THE subject which Iam going to deal with to-night, is one which
has exercised the minds of meteorologists ever since meteorology has
been in existence; that is to account for the various phenomena
relative to storms.

Ever since the invention of the Barometer, theories have been
advanced on tbe subject of its oscillations.

First, it was thought that the wind was the cause and not the
effect. But no reason was shewn why the wind blowing from one
direction should cause the mercury to rise, and from another direction
cause it to fall.

A great light was thrown upon the question when simultaneous
observations were plotted down, and lines of equal pressure, called
isobars, drawn. It was then discovered that these isobars invariably
.resolved themselves into a form approaching to that of a circle.

The next discovery made was that the wind always blew round the
circle with the lowest pressure to the left, thus blowing from opposite
- directions when the centre was an area of low or of high pressure.
This was the Cyclonic Theory.

According to this theory, every storm consists of a circular-shaped
-area of low pressure, round which the wind blew in a direction against
watch hands in the Northern Hemisphere, and with watch hands in
the Southern one. But here the whole truth had not been arrived at,
-and many accidents were caused by a sudden chopping of wind, quite
.at variance with the cyclonic theory.

Now although the greater number of storms are not entirely
-eyclonic, yet, as a matter of fact, some storms are true cyclones, and
-are experienced in the West and East Indies, as well as often being
found, of small extent, rolliag along between two _— opposing

-anti-cyclones.
H

236 A. G. Howard.— The [May 4..

The word anti-cyclone I do not like at all, as the area of high
pressure so called is caused by an advancing current which is opposed —
by another one, as will be seen in the body of the paper. I prefer the °
term ‘“‘ high pressure area,” which does not give any inference beyond |
assuming that there must be “ low pressure” ones, which is true, while
the term “‘anti-cyclone ” infers the existence of prevailing ‘ cyclones,”
while the truth is, that most of our storms are not entirely cyclonic.

Another theory which has been put forward, is the centripetal one.-
In this, the area of lowest pressure is assumed to be very small, and’
the winds to blow straight towards this point from all sides, the only~
modification being due to the earth’s revolution. Thus the very large
storms which cross the Indian Ocean would have the winds blowing.
spirally towards the centre, while the smaller tornadoes of North.
America would not shew this spiral development at all.

Here again the whole truth is not grasped. Spiral winds do blow,.
but they are not general. In tornadoes the wind, I believe, does blow
straight to the centre, but on this point I cannot speak with any
degree of certainty.

Another theory is to consider the area of lowest pressure as almost.
a line, the winds blowing straight towards it from all points. This
theory is true only for equatorial winds ; for polar winds it is utterly
at fault.

I have tried to set forth in the following paper a theory based upon:
the siftings of all these theories.

In investigating the question of Storms in South Africa, I have-
tried all the theories, but find each one unsatisfactory. I have thus,.
upon due consideration, placed the whole of them on one side, and
endeavoured, from actual observation and deduction, to arrive at a-
true understanding of this question, using the deserted theories as:
stepping stones to reach the result which I have tried to make clear
in the following pages. .

THE STORMS OF SOUTH AFRICA.

I wish, before entering into the question of the nature and origin:
of Storms, to have it distinctly understood what is meant by the term:
“storm.” A storm is nothing more than an atmospheric movement
tending to restore a ruptured equilibrium. Every loss of equilibrium,.
of however slight a nature, generates a storm in the strict sense of
the word, altacugh the winds evolved may be only slight. I say
advisedly, an atmospheric movement, although Iam aware many will

1887. ] Storms of South Africa, 237

disagree with me. They will point out numerous winds blowing,
where no storm is, as they assume, notably the trade winds. But 1
will answer them, that no wind whatever can blow without a distur-
bance of equilibrium, and that the trade winds blow constantly in
one direction because of the existence of a permanent storm along
the equator, the so-called belt of calms being in fact the line of
constant disturbance.

To understand the nature of storms correctly we must study the
distribution of the atmospheric pressure generally over the whole
earth. First, let us assume the earth at rest and no disturbing
influence whatever at work; what state would the atmosphere be
in? The whole atmosphere would be in a state of perfect calm.
Now, let us assume the sun to shine vertically over one spot on the
earth, what would ensue? In this case the air would rise perpen-
dicularly at that one spot, and a lower current would set in towards
it, while a higher one would flow from it, for a limited distance
around that spot. And now let us assume that the earth turns on
its axis, the sun being vertical over the equator. Here the sun’s
effect would travel completely round the earth, the result being a
belt of rising air, with a lower indraught and upper overflow for a
limited distance on either side. We will confine ourselves entirely
to the atmospheric movements in the southern hemisphere. Before
the upper current had reached the surface of the earth, a great.
quantity of air would have been drawn from the south towards the
equator, the indraw extending almost to the pole. Consequently
there would then be a vacancy to fill, and the upper current on
reaching the ground would continue its course towards the pole,
to fill this vacancy, till meeting the cold banks of bigh pressure
round the pole, it would momentarily force it back; but as the polar
pressure increased, this current would in its turn drive the equatorial
one back towards the equator, until having penetrated further than
necessary to restore equilibrium, a return oscillation would. take place
' and the polar current recede.

We thus see that the atmosphere would be divided into three
low pressure belts and four high pressure ones, that is to say,—a
low pressure belt round the earth at the equator ; two high pressure
ones over the north and south tropics ; and two low pressure ones in the
temperate zones, while two high pressure areas would rest over the
poles. Every outburst of solar energy would deepen the equatorial.

belt, and cause the air to be drawn in greater quantities from either:
H2

238 A. G. Howard.— The [May 4,

side, while the upper current being intensified would rush over the dense
bank of high pressure, and down through the temperate zone to the
pole, displacing the polar current, but by that very act giving strength
to this polar high pressure area and causing a return oscillation.

Now let us note the effect of the inclination of the earth’s axis,
whereby the sun appears to travel during six months over a belt of
47 degrees of latitude, that is, from 234° N. to 233° S. Owing to
this apparent motion of the sun, as the disturbed portion is always,
in the first instance, where the sun is vertical, the belts of high and
dow pressure are constantly oscillating north and south, one complete
oscillation taking twelve months to perform. Thus, Cape Colony,
when the sun is at its southern limit, has the south tropical belt of
high pressure to the south of it; but when the sun is at its northern
limit, this belt ‘is far to the north of us, and we are on the northern
edge of the temperate-zone area of low pressure. Were it not for
the unequal distribution of land and sea, the arrangement of atmos-
pheric pressure would be regular, and as sketched above, but as it
is, it is far from being so, although on the whole, it is as I have
described it, which is near enougi for the purpose of investigations
where Cape Colony alone is concerned.

By taking the mean barometer readings for different months, ana
extending over a number of years, isobaric charts have been compiled,
and these shew very clearly the distribution of high and low pressure.
By referring to one of these for January, it will be seen that a large
bank of high pressure lies to the south-west of us, and another to
the south-east, being joined together by a col or neck of compara-
tively lower pressure. The centre line of this area is the limit of the
ordinary influence of the equatorial indraw, but when great distur-
bances take place, the indraw extends further south, and the upper
current becomes intensified, bringing violent south-easters over the
Colony, and storms in the area of low pressure to the south of us,
which after a definite period, return from the south on to the Colony,
with north-west winds and rain.

To the north of the Colony, and stretching well to the interior of
Africa, isa wild Karoo, hot ‘and dry, called the Kalahari Desert,
with extensions to the West Coast and down to Namaqualand. This
‘hot plain plays an important part in our Colonial meteorology. The
constant heat generates a const:nt upward flow of air, and a
-consequent surrounding circulation. Thus over the Orange Free
‘State and at Kimberley the wind flowing round this area is north or

1887.] Storms of South Africa. 239

north-east. A portion of the south-east trade flowing from the
high pressure area over the South Indian Ocean is deflected and
drawn towards this area of low pressure, and intensifies the north
wind which flows on to the Colony. How far the geographical
distribution of mountains and plains affect this deflection is an open
question, but I have no doubt as important a part is played by these
in South Africa as in other places.

When any great disturbance takes place at the equator, a strong
current sets in off the tropical bank, towards the point of disturbance,
and the portion which mingles with the northerly current before-
mentioned, increases its intensity considerably, and forces it further
on to the Colony. Here it meets the south-east current of the trades,
and a semi-cyclonic movement is generated, but as the pressure of
the advancing and opposing currents is greater than the lateral
pressure, the area of disturbance formed will be of an oval shape,
an ellipse in fact, the minor axis being along the point of greatest
pressure. Various modifications of this form are experienced when
the advancing and opposing currents do not meet at an angle of
180° but at a smaller one. —

The north wind, having passed over a tropical portion of the earth,
is, as a rule, warmer than the south-east one, consequently it flows
up and over the latter, while the south-east wind is deflected and
flows more easterly, until reaching the edge of the high pressure
area to the south-west of us, the combined forces of the winds
increase their power to a very great extent.

So that when an area of low pressure extends across the Colony
the winds will flow direct in to it from the north-east, north and
north-west, but will flow round it on the south and west sides, as
east and south-east winds.

As the power of the north current increases, it forces its way on to
the Colony, the area of low pressure thus advancing, until the
constant overflow above on to the area supplying the south wind,
and its consequent banking up, causes a return oscillation. At the
time when the two currents are stationary (which sometimes lasts
for days, when the currents are balanced in intensity) the winds
blow strongest, and often independent cyclones form in the low
pressure area between them and roll off to the east. This I have
noticed over and over again. When the south current has gained
the victory, it gradually pushes the north one back again, but as
this south current generally comes from the south-west, in the form

240 A. G. Howard.— The [May 4,

of a high pressure wedge, the elongated area of low pressure over
the Colony is split in two, one portion of which recedes to the north,
and the other as a cyclone rolls off to the east, bringing storms to
Natal and the Eastern Province.

Sometimes the northern current flows right across the Colony, the
area of low pressure being driven down to the south-east of us.
Then if the south current sets in the two will cvalesce, and a very
high so-called anti-cyclone be the result. I need scarcely explain
that when two currents, flowing in comparatively the same direction,
coalesce, the pressure is increased without any cyclonic movement,
but when the two currents are opposed, a low pressure area is the
result, and often independent cyclones are formed.

When the upper north-west equatorial current is intense it flows
down into the area of low pressure to the south of us with great force,
and meeting the polar current, drives it back, a storm being the result,
the north-west wind blowing straight to the lowest pressure, and the
south-east winds being cyclonic. As soon as this current has
expended its force, and the polar current becomes banked up and
increased in intensity, a return oscillation (as before described) takes
place, the distance to which this return storm pushes to the north
being proportionate to the intensity of the north-west upper current
in the first place. These storms come on to the Colony from the
south-west, and even west, and are preceded by easterly and north-
easterly winds of no very great intensity. As the area of low
pressure advances the wind becomes more northerly, till when the
barometer is at its lowest, the wind is generally north-west, but goes
round very smartly to the west. This change is usually accompanied
by heavy squalls and rain.

To more fully explain the nature of storms, and bow they are
generated by two opposing currents, I have prepared some diagrams,
which I will now refer to.

Fig. 1 shews a section through a storm on the plane of the line

of motion.

1887. ] Storms of South Africa. 241

Eis the equatorial current and D the polar one. When the two
currents come into contact with one another, as E isa rising wind
and D a falling one, the rising one will naturally flow up and over
the falling one, the line of meeting being shewn at A B. Both
enrrents flow in alnaost parallel lines at different heights, one having
a downward and the other an upward tendency, and wherever either
current meets the line A B, the particles of air are carried upwards
towards B. At F they reach a point of equilibrium, but being forced
upwards by the particles below them, they flow outwards on either
side and compensate for the loss sustained by the lower currents.

Now it is evident that if there is an increase of atmosphere at N
it will press unduly on D and the whole system will move towards
the south. A vacancy will be caused at A, by the upward current
from A to B, and the surrounding surface winds will rush in to
compensate for the loss, the general direction of the winds being

.as shewn on Fig. 2.

(Fig. 2.)

Suppose the initial banking up of E (Fig. 1), which caused the
“motion, to cease; as the motion is now towards the south, a point
would be ultimately reached where the weights at D and N would
be balanced.

But the depression will not stop here. Dynamic force has to be
. overcome, and so the disturbance will still travel to the south, till
the increased banking up of D will not allow of its further motion,
and it will consequently come to a standstill.

But the greatest weight of air being now at D, the whole system
will be forced back and be pushed against E in a similar manner, to
be in its turn beaten back to D, and so the oscillation will be kept
‘up till equilibrium is restored.

Sometimes the two currents will bank up simultaneously. The
depression will then be motionless, but the winds will be very strong

242 A. G. Howard.— The [May 4,.

and the barometer oscillate violently. Inequalities of surface contour,
or patches of intensely heated soil will be enough to generate inde-
pendent cyclones, which, once formed, will roll along between the
two currents and pass away to the east. These little storms are
very annoying in upsetting all the pre-arrangements of the forecaster,
and very often make him look foolish before the world.

I have observed the two opposing currents remain stationary for
a week over the Colony, and cyclone after cyclone roll along the
intervening area.

On Fig. 3 I have embraced more of the two currents, and the:
storm in the form of an isobaric chart.

(Fig. 3.)
E is the equatorial current and D the polar one, A being the area

of low pressure at the plane of meeting, close to the surface of the
ground. It will be noticed that the winds flow off the areas of high
pressure D and E, first in straight lines on all sides, which by the
revolution of the earth are gradually deflected in a direction opposite
to the motion of the hands of a watch on its face. Were there no
disturbing element, these winds would become more and more
circular ; but coming under the influence of the area of low pressure,
they are drawn towards it from all sides. Those of the equatorial
current E are seen to blow straight in, and those from the polar one
D being deflected round the area in a direction similar to watch hands..

I will now refer to Fig. 1 again.

All atmospheric currents as they travel along contain a certain
amount of moisture, although this may be in a state of invisibility.
It is a well-known fact that the temperature decreases as we ascend
into the atmosphere, and also that if atmosphere containing moisture
be carried to an altitude where the temperature is lower than the.
dew point of its original position, the moisture condenses, and clouds.

form.

1887.] Storms of South Africa. 243:

Bearing this in mind it will be noticed that, as the air at A is
earried up to B, and contains moisture in an invisible state, this
moisture will condense and form clouds at that level. As fresh moist
air rushes up, fresh clouds will be formed, each one being larger and
more complete than the last, till at A the type will be the large
cumulus and cumulo-stratus. As the cloud forming moisture is
eatried up by the ascending current, a portion will be conveyed back.
by the return overflow above and being precipitated through the
_atmosphere at N form various sorts of clouds there. According to:
the amount of moisture carried up, so will the clouds at N accumulate,
and ultimately rain will fall. The direction of the clouds will be
parallel to G.H.K.L. on Fig. 2. Those at G will be faint horizontal
streaks of cirro-stratus, sometimes barely visible to the eye. Follow--
ing these at H will come nodules of cirro-cumulus. The pinnacles:
of these nodules penetrating into the great west upper current above
the line B.M. (on Fig. 1) will be blown into thin streaks or threads.
and form the cirro-filum or thread cirrus. Simultaneous with the
dispersion of the upper portions of these nodules, a precipitation will
take place into the lower current, the rain being blown towards A
on Fig. 1. At K and L (Fig. 2) the clouds will be larger and more
perfect in form, till at A, the heavy cumulus, cumulo-stratus and
nimbus are formed. Beyond A in the equatorial current, hard
rounded cumulus, with intermingled stratus merging into cirro--
cumulus and high mottled cirrus will be found. No cirro-stratus
will be found on this side of the centre. All along the line A.B. (Fig..
1) the clouds form, and are apt to impinge into the upper current..
When this is the case, a precipitation is sure to take place, and if
the altitude is not too great, will reach the ground, hence the area
of precipitation (shewn by the dotted lines on Fig. 2) is always:
more on the polar side than on the equatorial one. This is why we:
have more rain, with our winter storms, after the centre has passed
than before.

And now let us study for a few minutes the movements of the
barometer during the passing of the system. E (Fig. 1) is a warm
eurrent and consequently light, while D is a cold one and of course
heavy, but if the whole system is moving towards the south, the
intensity of E must be great enough to overcome the weight of D,
and consequently the pressure at N must be greater than at D. From
€ to A the heavier current is gradually becoming less, the current E
being much lighter, hence the barometer will gradually fall from

244 A. G. Howard.— The [May 4,

C to A, and as the pressure at N is greater than at D, the barometer
will increase from A to N. ;

Hence whichever way the system is travelling, the barometer will
fall till A has passed, but there will be a great difference in the
manner of the changes, for while the gradient from C to A is gradual,
that from N to A is very abrupt.

So that if with a north-east or north wind, the barometer falls very
suddenly, we may almost be certain of rain falling when the barometer
begins to rise, especially if heavy cumulus or cumulo-stratus clouds
are seen to the south-west, from which direction the following winds
will blow.

When a depression is advancing on us from the north-west, the
first indication of its approach is a sudden rise of the barometer, and
the appearance of long horizontal strips of cirro-stratus to the north-
west. These strips follow one another and rise higher and higher.
‘Cirro-filam are often seen before this, in long parallel threads from
north to south. When the cirro-stratus has reached the zenith, banks
of other and lower cirri come up from the north-west, and the baro-
meter begins to fall, the wind then blowing from the east or south-
east. As the depression advances, heavier and lower banks of clouds
come up till the whole sky is overcast and rain begins to fall. As
soon as the barometer begins to rise, which it does suddenly, rain
falls in heavy squalls, and the wind blows strong from _ the
north-west. The storm has passed and fine weather follows.

At Cape Town we very seldom have the centre of such a depression
pass over us, but when it does, a black south-easter is followed by
showers from toe north-west.

In summer time the centre generally passes to the north-east of
us, so that the winds,are easterly as the centre approaches, south as
it passes, and west after it has passed. Rain very seldom falls here,
‘but they are the great rain bringers of the East and Natal.

In winter the centre generally passes to the south-west of us,
the wind being then from the north-east as the centre approaches,
then north and north-west, and finally west, with rain squalls
ending in fine weather.

Some of our severest winter storms are of this type. In these the
greatest amount of rain falls before the barometer rises.

The great majority of our winter storms are of a different type. In
these the polar current is displacing the equatorial one, hence the
sudden manner in which they come upon us. The advance wind of a

1887. ] Storms of South Africa. 245

-storm of this type is generally from the north, which changes to the
north-west as the centre approaches. As the centre passes, which it
-does to the south of us, the wind chops round to the west with heavy
rain and squalls, which continue as the barometer rises. Fine
-weather follows with a south-west wind. With these storms the
greatest amount of rain falls after the centre has passed.

These depressions bring rain to this end of the Colony during
-winter and to the other end during summer. Owing to the fact that
“these storms generally travel alon t he course of the L’Agulhas
-ecurrent, the rain falls in the east with a south wind.

When a depression travels as rapidly as the advance winds blow, a
_dead calm is very often experienced in front of the storm.

This is very often the case, especially during summer, when the

storms come from the north-west.

I have often noticed a gradient between Cape L’Agulhas and Cape
~Yown, which ought to have brought a south-east gale, but only light

winds followed, the fact being that the depression, although deep, was
travelling as fast towards the east as the advance indraw, in other
-words it was keeping up with the wind and counteracting its
“intensity.

I have assumed in all these examples that the two opposing
currents are pressing directly against each other; but such is very
seldom the case, they generally abut obliquely and sometimes very

much so, and then instead of travelling in the direction of the line of
the minor axis of the low pressure area, they travel along a line
formed by the resultant of the two opposing currents, and the form of
the depression changes from that of an ellipse to almost any shape.

And now before concluding, I should like to say a word or two
‘about sun spots, or rather I should say solar storms. It will be

remembered that in a former paper of mine, I laid before you the fact,
from actual observation, that upon a sun spot reaching the centre of
the sun, various known winds blew at regular intervals thereafter ;
thus from two to three days after, a south-easter was sure to blow
during the summer months, while eleven days after, north-west or
"west winds were experienced.

Now the reason of this is shewn in this paper. As soon as the
atmosphere at the equator is affected, an upper current rushes towards
the poles. It takes two or three days to reach the latitude of Cape
Colony, at which date the south wind blows strongly owing to the
atmosphere being banked up to the south of us. The upper current

246 A, G. Howard.—The Storms of South Africa. [May 4,

then follows the sequence before mentioned and comes upon us elever
days after as a south-west depression.

I have not contiuued my observations on sun spots for the reason
that it is impossible for one individual to do everything, and I have
found no one interested enough to study this question. Moreover, I
do not believe all solar disturbances are visible to us, so that to study
this question properly comparison should be made with the observa-
tions of magnetical disturbances, which are caused by variations in the:
sun, and to do this is a study in itself, so that did I devote my spare-
time to this, I would have to do this alone to the detriment of my
other observations, and this I do not care to do.

But if there are any who would like to enter into this investigation,-
I would suggest the tabulation of magnetical storms, and these I am-
certain would determine the period of depressions and their nature-
also. Thus, I have no doubt but that two days after a magnetical:
storm, a strong north-west upper current flows over Cape Colony,-
and the barometer banks up to the south, with strong south-east:
winds. At eleven days after a similar disturbance, a south-west:
storm of the winter type will come, and so on, regular fixed periods
for definite storms. I place the consideration of this question before
any one who wishes to further the interests of meteorology.

There is no doubt that electricity plays an important part in our
weather. In fact, time may shew that electricity is the one great:
and sole agent at work, and the sun the great electromotor, the earth
being the accumulator.

I do not know whether any present have noticed the manner in.
which cumulus clouds group, but I have, often. As faras my obser--
vations have extended at the Cape, they seem to aggregate in:
horizontal banks of a definite width and parallel to each other, the-
line of stratification being along the magnetic meridians. I do not
bring forward any reason to account for this, but merely give it as an:
authenticated observation, leaving it for the future to decide what the:
meaning may be.

ADOLPH G. HOWARD.
Cape Town,
30th March, 1887.

ON THE ADULTERATION OF BRANDY.
By R. Marvotnu, Pu.D., M.A.
[READ 29TH JUNE, 1887.]

‘THE subject of the adulteration of brandy has been ventilated in
-the Colonial newspapers from time to time, not only here in Cape
‘Town but also elsewhere. During my stay at Kimberley, about
eighteen months ago, I read there similar complaints about the
‘injurious properties of the brandy, to those which I had heard here.

It seemed to be the general opinion that most of the canteen-
keepers were dangerous compounders of poisons, who took the brains
out of the unsuspecting natives by means of blue-stone, oil of vitriol,
tobacco-extract or cayenne pepper.

I thought it therefore worth while to investigate the question
-and procured four samples of brandy, but having there no analytical
apparatus at my disposal, I took the samples with me to Cape Town.
This was in the beginning of 1886.

Another journey however, which took me from Cape Town for
-several months, prevented me from taking up the postponed analysis ;
and when I returned from the interior, the subject had slipped out
-of my mind.

It was only about February last, when some remarks in the
newspapers reminded me again how desirable it was to ascertain
the nature of the virulent poison that was maddening the stalwart
Kafir in the streets of Kimberley and the jolly sailor who landed on
our shores.

I employed a common workman for the purchase of the samples,
‘which were taken from different canteens of the town. Up to the
‘present I have analysed twenty-four samples of brandy, four from
Kimberley, bought there last year, and twenty from Cape Town,
bought during the months March, April and May. .

I may state at once that none of these samples contained any
foreign ingredients detrimental to health. My investigations con-
firm therefore the results which were obtained at the Excise Depart-
ment by the examination of forty-seven samples of brandy, and we

248 R. Marloth, Ph.D., M.A.—-On [June 29,

may therefrom draw the conclusion, that very little, if any at all,
adulteration of brandy takes place in our canteens,—adulteration at
least in the restricted sense of the word as we use it out here, alluding
only to the addition of health-destroying materials. |

Although the brandies which I have analysed did not contain any-
artificially added poison, I cannot consider them to be a harmless.
drink. Harmless I mean of course without regard to the effects.
which the alcohol itself has on the consumer. The majority of the -
samples contained a considerable amount of fusel-oil, agreeing in
this respect with those which have been examined by the Excise- -
officer.

To prevent any misunderstanding, I may be allowed to consider-
in greater detail this unpleasant body, the fusel-oil.

The alcoholic fermentation is often described as the splitting —
up of sugar into alcohol and carbonic acid, effected by the action
of some living vegetable cells, commonly called the “yeast.” Busy-
this is a very rough and incomplete definition of the process, which
is not at all such a simple one. On the contrary it is a very com--
plicated matter, the attempt to explain which has given rise to mary
theories, and which is yet far from being fully understood. We.
know that whenever such fermentation takes place a considerable.
number of other chemical substances are formed, 94 per cent. only of ©
the sugar present in the liquid is—as Pasteur has shown—trans--
formed into alcohol and carbonic acid, the other six per cent. supplies
the material for the formation of the accompanying substances. The-
principal by-products are glycerine, succinic acid, som3 compound’
ethers, as for instance acetic ether and several other alcohols. In
chemical language the name alcohol comprises a whole class of
substances which are composed according to a similar formula. The-
five first members of this series are the methyl, ethyl, propyl, butyl.
and amyl-aleohols.

Speaking generally however of “alcohol”? we always mean _the-
second of the series, the ethyl-alcohol, just as we use the word
“salt” in a specific sense, although there are thousands of different
salts known to the chemist.

There seems to be a widespread opinion, that the nature of alcohol
differs according to the material it is made from. That is a
misunderstanding of long established facts. The alcohol is exactly
the same in all the fermented and distilled liquors, chemically and
physically. It is the ame substance that men are eager to produce:

1887. | the Adulteration of Brandy. 249

in their alcoholic beverages all over the world, whether they ferment the
sap of the African palm or the milk of Caucasian mares, whether they
distil it from the grain that grows in the valleys of Scotland, from the.
potato of the German plains, or from the noble grape on the banks of
the Charente in the West of France and on the hills of the Paar] in
our neighbourhood. It is always this ethyl-alcohol (C2 Hy, O.)

The difference of the various products lies only in the accompanying.
substances, and as far as the distilled spirits are concerned, only in the-
bouquet.

What is the bouquet ? you will ask. It is a very variable, very
delicate and complicated thing, and I can name here only a few of its
constituents. You will remember that during the fermentation all the
chemical compounds, which I mentioned, are formed. ‘Their relative
proportions and absolute quantities vary considerably, according to the.
fermenting liquid and the character of the fermenting agents, the
yeast. Also here cleanliness is of the highest importance. The
purer the ferment itself, the purer is also the product. Recent
investigations with carefully prepared ferments (yeast) have shown
that it is possible to obtain almost pure alcohol, which is not accom-
panied by any fusel-oil at all.

This portion of the by-products of fermentation, namely the volatile
ethers and acids, pass easily over during the beginning of the distilla-
tion ; the glycerine and the succinic acid, being not volatile, remain
of course in the still with the refuse- wine, and the other alcohols with
a much higher boiling point than et hyl-alcohol, should equally remain,
in the still. But they do not, just as water evaporates already much
below its boiling point, in fact at all temperatures and even in its
solid state, as ice or snow, so these alcohols are volatilized with the.
vapours of the ethyl-alcohol and water. Their quantity in the
products will of course depend on the amount that was present in the
original liquid and on the care besto-ved upon it during the distillation.
The three alcohols with a higher atomic formula than the ethyl-
alcohol form principally the compound which is called “ fusel-oil.”
The fusel-oil of the wine is different from that of the grain and _ this
again from that of the potato, but they all contain these alcohols in
various proportions.

It isa fact which has long been known, that fusel-oil is highly
injurious to health, and especially that of the potato has always been
noted as the most objectionable one of the family, but only recent.
experiments have shown the reason for these facts.

250 R. Marloth, Ph.D., M.A.—On [June 29,

It was Professor Dujardin-Beaumetz in France, who ascertained
the effects of these alcohols on dogs. The results of his experiments
establisb the highly interesting fact, that the higher in the series
an alcohol stands the more toxic it is, and the degree of toxicity
follows almost in a mathematical ratio the atomic formula. He has
determined the medium toxic dose for the various alcohols, calcu-
lated on the weight of the dog and reduced to a unit in kilogrammes,
and he obtained as the result the following series: Ethyl-alcohol,
7753 propyl 3°75 ;. lentyl, 1°85; amyl, 1-5. You are, of course;
aware of the fact that the alcohol contained in brandy or wine or
elsewhere is a poison. There is a toxic dose for alcohol just as well
as for strychnine. It has happened often enough that a man has
been killed by taking too large a dose of spirits, The toxic dose
for dogs being 7°75 grammes for each kilogramme of weight, a
terrier, weighing for instance five pounds, would require one ounce
of ethyl-aleohol to be killed. But in giving him _ propyl-aleohol,
which is the first of the fusel-oil series, half an ounce would produce
the same effect, whilst the anyl-aleohol would do it already with 90
drops, being more than five times as toxic as the ethyl-alcohol. The
latter is, you remember, the alcohol par excellence, the former with
five atoms of carbon is the fusel-oil “par excellence.” It is this
alcohol which forms the main portion of the potato and grain fusel
oils, and therefore the obnoxious properties of rude potato and grain-
spirits are easily understood. The spirit carefully distilled from
good wine contains very little of these more toxic alcohols, but in
spirits from badly fermented wine their quantity increases, if the
distillation is not carried on in such a manner as to prevent their
being mixed with the spirit in the receiver.

Mr. Crowe’s suggestions in his report to Parliament deserve the
full attention of all brandy-distilling farmers, for if the stills are
improved in such a way as he recommends a great portion of the
fusel-oil will be separated from the brandy.

I may be allowed to repeat that the nature and the quantity of
the fusel-oil alone make a spirit more or less objectionable from a
hygienic point, of view, and that there is not the slightest reason
for objecting to the use of rectified potato or grain spirits instead
of wine-spirit. On the contrary. With the modern appliances,
which a professional distiller in Europe is compelled to use at
present, for economy’s sake, such spirit is produced of a greater
purity than any other kind, and it is this spirit chiefly which is used

1887. } the Adulteration of Brandy. 251

for making up not only brandies, ete., but also for strengthening
wines, not on account of its cheapness only, but for the sake of
its purity.

Much has been said against a practice which is universal at home,
that of making up brandy by mixing it with other spirits, obtained
from grain or potatoes, or by manufacturing it entirely from the
latter and flavouring it by the addition of some essence.

But how can it be otherwise, when the demand for the article far
_ surpasses the production ? Since the phylloxera has made such
ravages with the vines of France, the production of genuine French
brandy has fallen from about 60,000 leaguers in 1875 down to 842
leaguers in 1879 and has only risen again to 2,220 in 1882. It is
obvious, as Monsieur Dujardin-Beaumetz says, that a millionaire only
is able to procure nowadays the genuine article for his table, and,
paying even as much as a guinea fora bottle, he is not certain that
he gets a really pure article.

The consumption of brandy not having decreased since that time, it:
stands to reason that the bulk of the article which is in the trade at
present, including the favourite brands so largely used in this colony,
is made up artificially. What a wonderful chance is offered here to a
wine-producing country like the Cape !

But I must state at once that from a hygienic point of view—and I
have here nothing to do with the commercial side of the question—
this spurious brandy, made from the vile potato-spirit, is by far
preferable to the genuine article as the Cape-farmer produces it at
present, for the former is free from the more toxic aleohols which the
latter generally contains.

It has been suggested that the evil is principally due to the want of
age of our brandy. ‘That is true toa certain extent; but never will
such brandies as I have met with here, become pleasant and wholesome,
even if kept for twenty years. The want of care during the fermenta--.
tion of the wine and the gross negligence during its distillation impart
to it such an amount of fusel-oil and empyreumatic products that no.
length of time can remove them.

Concluding my little paper, I feel bound to touch another side of
the subject before us.

What steps should our legislature take with regard to this adul-.
teration-question ? All the greater States of Europe have found it
necessary to promulgate laws against the numerous adulterations to

which articles of food and drink are subjected. In principle these.
I

252 R. Marloth,Ph.D., M.A.— On the Adulteration of Brandy. [June29,

various laws are similar to the British Food and Drugs-adulteration
Act of 1875. They forbid not only the sale of any food or drink,
which contain ingredients injurious to health, but also the sale of
any such gocds, which are not of the nature, substance and quality
indicated by the name. They inflict. comparatively high penalties
on the man who sells a mixture of milk and water under the name
of milk, or coffee mixed with chicory under the plain name of coffee,
or oleomargarine, alias butterine, for butter. The German Supreme
Court at Leipzig for instance confirmed only lately the sentence of
several months’ imprisonment, which a Provincial Court had passed
on a spirit-dealer. And this man had done nothing but manufac-
ture three leaguers of Jamaica-rum out of one leaguer of the genuine
article. It is doubtful whether our legislature is already sufficiently
impressed with the necessity of protecting our pockets against such
tricks of dishonest tradesmen, but J think that it is the duty of the
legislature of every country to protect the lives and the health of
its inhabitants.

Some people may say that nobody is compelled to drink brandy,
but we must deal with men as they are and not as they ought to be.
The many efforts put forth by various governments to check the
consumption of distilled liquors have thus far failed. Neither increased
taxation of spirits nor severe penalties against drunkenness have
availed and in spite of the strenuous efforts of the temperance
societies the number of those who stick to alcoholism is immense.
But if we cannot abolish the use of alcohol we can very well diminish
the dreadful consequences of it by preventing the sale of a stuff
which is overcharged with health-destroying ingredients, and I dare
to express the hope, that the time is not very far when the sale of
food and drink which are detrimental to human life will be as great
a crime at the Cape as it is in London, Paris or Berlin.

APPROXIMATE TIDE-CONSTANTS FOR TABLE BAY
AND ALGOA BAY.

By W. H. Finuay, M.A.
[READ 31sT AUGUST, 1887.]

At the suggestion of H.M. Astronomer, D. Gill, Esq., self-
- registering tide-gauges of the most approved pattern were erected in
1880 at Cape Town and Port Elizabeth by the respective Harbour
Boards : and the tracings of several years’ tides are now available for
-reduction. It is to be hoped that arrangements will soon be made for
-a complete discussion of these curves and for an accurate prediction of
future tides. Meanwhile I have thought it would be of considerable
interest to obtain some preliminary results with regard to the mone
‘important of the tidal constituents, and to see in the case of Table
Bay whether any correction is indicated to the data published in the
Shipping Gazette, 1853, and used for the formation of the tide-tables
to the present day. These data were derived from 4,099 observations
-of the time of high water at the Naval Yard, Simon’s Town, during
the years 1840-1848. From previous observations in 1834 and 1835
with two temporary gauges, one at Simon’s Bay and the other at the
“South Jetty, Table Bay (near the Imhoff Battery), the conclusion
‘was arrived at that there was no sensible difference between the time
of high water in Simon’s Bay and in Table Bay: and the results of
the Simon’s Bay observations were adopted without alteration. No
:information, however, is given in the Shipping Gazette about the
heights of the different high waters. Tide-gauge diagrams have, I
believe, been regularly filed for many years previous to 1880, but no
~attempt (so far as I know) has ever been made to discuss them.
The height of the tide at any place may be expressed as the sum of
-a number of simple harmonic functions of the time, the periods of the
functions being the same as the periods of certain terms in the theory
of the Sun and Moon. The analytical expression for such a function
As
A cos nt + B sin né, or R cos (nt — 8),

‘where ¢ denotes the time elapsed from some starting-point, is the
12 |

254 W. H. Finlay, M.A.—Approximate Tide- _[ Aug. 31, -

‘speed’ of the tide (so that the function repeats itself in a time =2),..
n

R is the amplitude and « the epoch. Each such component is called a ~
tide. The actual height of the tide therefore at any time ¢ is equated |
to the expression

A, + Ri cos (7, ¢ — 1) + Re cos (%2 tf — &) + &e.

where A, is the height of mean sea-level above some assumed datum- -
line ; and the solution of a large number of equations formed in this
way determines the most probable values of the constants involved.

Prof. G. H. Darwin has shown that it is possible to deduce very ~
approximate values of six of the most important tides from observ- -
ations taken every hour for a month. These are the lunar, solar and.
luni-solar semi-diurnal tides ; and the luni-solar, lunar and solar diurnal
tides : they will be referred to by the letters Ms, So, Ke, Ki, O and-
P respectively. Of these the two first are usually much the largest
and most important, and they are the only ones that can be taken into
account in forming a mean tide-table to apply approximately through--
out the year. But it should be understood that such a table must
necessarily be rough: the diurnal tides are neglected and will have-
the effect of making the predicted times of high water differ from the-
observed times by about the same amount for the morning and
evening tides but in different directions, and there will be inequalities
depending on the moon’s declination and distance from the earth. If
it be thought worth while to allow for these inequalities, the results of
the present investigation will allow of its being done: but as a
month’s observations are not sufficient to determine the elliptic tides
and as the time and height of high water are to some extent depen--
dent on the meteorological conditions obtaining ai the time, it is
perhaps scareely worth while to incur the extra labour of the com-
putations. For Table Bay I have worked up two series, one in 1885,
November, and one in 1887, May: the results from the two series:
showed a most satisfactory agreement. For Algoa Bay I have taken
one series in 1886, April. I have ¢ssumed that the height of the tide
is affected to the extent of one foot by a change of one inch in the-
barometer reading, and corrections have been applied to reduce the
readings to a mean height of the barometer of 80 inches.

Putting H for the semi-range of a tide, and K for the constant.
angle of retardation or ‘ lag,’ I find

Or

~1887.] Constants for Table Bay and Algoa Bay. 25

TABLE I,
TABLE Bay. | ALGOA Bay.
h h
Age’ of tide = 26°4 | nea)
_Mean height above ft it
datum-line = 2°37 | == 2°34

ft ft

Ha=1'60 _ (H’ = 0°19 aL een

My, Ky M2 Ky
bees e7o oc (ak 2.1940 aye

ft it it
H, =0°68 H, = 0:06 He OnSe EE = 0-095
Se O Se O

Ka= 93° Kev 250- K, = 128° Ke —-280-
ft iy ft ft it
H” =0°18 H,= 0°06 H’ =0:23 H, = 0°05
Ke, P Ky P
K" = 93° K, = 124° K” = 128° Ke = 146°
h m h m
~¢Mean’ establishment = 2 1 == 21

“The diurnal tides are therefore small at both places, but they are quite
sensible.

The ‘mean’ establishment hitherto used for Table Bay is 2% 43™,

:so that the considerable correction of 24" must be applied to the
-average of the predicted times of high water. This correction to the
-old value may be due partly to the different position of the gauge in
the Bay, but more probably to an error in the statement that the times
.of high water at the Naval Yard, Simon’s Bay, and at the South
-Jetty, Cape Town, are coincident: for unless special precautions are
taken in the erection of a tide-gauge to annul the effects of wave-
disturbance it is no easy matter to determine the time of high water
‘from the diagram to a good many minutes.

The ‘vulgar’ establishment, or time of high water at full and
change of the Moon, is 2" 33". The ‘ vulgar’ establishment given for
Algoa Bay on the charts is 4", hut Capt. Skead, R.N., has pointed out
that the observations on which this result depends were taken at a

Station some way up the river and that the value for the Bay should
‘be considerably less : my results make it 38 39”,

256 W. H. Finlay, M.A.—Approximate Tide- _ [ Aug. 81,..

A ‘mean’ tide-table, sufficient for purposes of approximately
predicting the time of high water, can easily be formed by a graphical
process from the above results for the M. and S. tides.

The local mean time of the Moon’s transit is to be converted into
angle at the rate of 30° to the hour and from it the angle (K, — 29
K,,) subtracted: call the result a Then on any convenient scale
take a straight line SO equa! to H, and preduce it to any point A.

With Oas centre and H,, as radius describe a circle: and from the

point O draw a straight line
OM making with AO an angle
equal to x and cutting the circle
in M.

Then SM is the height of the
tide, and the angle OMS con-
verted to time at the rate of 29°
to the hour is the correction to
be applied to the mean establish-

ment to find the interval by
which the time of high water follows the moon’s transit over the
meridian.

The correction is subtractive if 2 be less than 180°, additive if
greater.

Table IL is sucha table ; it gives for Table Bay and Algoa Bay
the time of high water and the height of the tide above the datum-
line corresponding to each half hour of the Moon’s time of passing”
the meridian. The hours of the Moon’s transit are reckoned from.
0» to 24", commencing at noon: and it is to be understood that when-
the time of transit is greater than 12" the correspoading time of highs
water is to bejincreased by 122.

1887 |. Constants for Table Bay and Algoa Bay. Dat

Taste II,
TABLE BAy. ALGOA BAY.
Local Time |

Mac ane ee Ba ls ae Height
Water. Tide. Water. Tide.

hee m ley aga h m ft h m ft
PO. Or om 196 0,1 29 33 4°61 3 39 4°87
O 30 or 12 380 De Ayes 4°65 3 9 4°92
Pe Oror ts) 0 3 18 4-65 4 20 4:93
1°30) or 13 30°). 3.736 4-61 4 40 4°91
220 0F- 14: 0 3 8s 4°59 5) 0) 4°84
2-30; on 14230 4 19 4-46 oe Zh ae
3 OF or. to- 0 4 4] 4°34 do 42 4°61
3 80 or 15 380 3 4 4-19 6* 4 4°45
H Oo 1G, 01 = 20) 4-08 6 98 | 4-96
4 30 or 16 30 5 BT 3°86 6 54 4°05
a OF O17) O 6 28 Ort (2S 3°84
a OU OF 17 30 i 5) SO ay Le or 3°63
6 Oor 18 O i 40 3°38 8 38 3°44
6 30 or 18 380 Se oF 3°30 9 28 3°31
71105 or 219) 0 9 30 3°30 KO Ae 3°07
7 30 or 19 30 10 20 Se Ba T3.20 3°34
8 0 or 20. 0 11 3 3°50 12 8 3°49
8 30 or 20 380 ll 40 3°70 12 46 3°68
9:0 -ofn21—- 0 Ee bt 3°84 18 19 3°91
9 30 or 21 30 E239 4°02 Let 2 ee 4°11
lO. 0. or 22 20 13 4 4°18 14 138 4°31
10 30 or 22 30 138 28 4°33 14 36 4°50
b= O-orsZ25. 0 13 50 4°45 14 358 4°65
Il. 30 or 23 30 | .14 12 4°55 ie, bo 4°78

258 W.H. Finlay, M.A.— Approximate Tide- Constants, &c. [ Aug. 31,

if we desire to take account of the parallactic and declinational
corrections we may proceed as follows :—

For SO (in above fig.) take the value 1°086 p, cos? 6, H, where p,
is the cube of the ratio of the Sun’s parallax at the time under
consideration to the mean parallax, and 6 is the Sun’s declination.
Then from Tables III and IV take the small corrections depending on
the Moon’s parallax and declination, remembering that these correc-
tions are to be taken out for the Moon’s position at a time anterior to
the high water by the ‘ age.’

TasurE III. Taste IV.

Argument—Moon’s Declination.

Argument—Minutes of
Moon’s Parallax in
excess or defect of

fe) h
+2°0 |+0°07

bo
©
—
~IJ
Qn
S
_—
—_

1:8 | -06
H eee 10° |. 0-408 | 4-3 | 2 405
Mk 15 |+0-02 |+0-4/+4 -01

5 0-42 3

—0°8 °03

The height and time of high water can be found from the figure (as in
the general case) if we substitute
Hy + o& Rm + 62 Rm for OM
x + 6. K,, for the angle x
and add the time 6, to the mean establishment. We can also easily
find an approximate value of the largest diurnal tide :—

Let ¢ be the time of H.W. and A the height of any afternoon tide
computed from the mean tide-table. Find z’ (= K’ — Sun’s long. +
90°) and subtract it from ¢ converted into angle at the rate of 15° to
H’ Sind

h

the hour: call the remainder \: then is the correction to ¢

in decimals of an hour.

and H’ cos X is the correction to h.
The corrections to the morning tide may be taken as the same in
amount but of opposite sign.

THE BAROMETER: ITS REDUCTION TO SEA LEVEL.
By A. G. Howarp.

[READ 28TH SEPTEMBER, 1887.]

THE subject of my paper is the reduction of an indicated
atmospheric pressure at an elevated station to that which it would be
were the earth below that station removed, and the observation of
pressure made at the sea level. The object of thus reducing the
indicated pressures to one datum, is for the purpose of charting a
number of simultaneous observations for comparison and for the
drawing of isobars or lines of equal pressure. The datum employed is
usually the mean sea level.

The true formula for this reduction has not yet been developed, and
iit is my firm opinion, that as far as reductions of pressures on isolated
.mountains are concerned no formula will ever be produced for giving
‘the true sea-level equivalent. The local eddies, and alterations of
temperature, pressure and humidity are such, in such a position, not
‘only at the station itself but at varying heights, that the formula
‘which would be correct at one time would give very erroneous results
cat another.

But on elevated table lands the conditions are totally different ; in
such a position there are no local eddies whirling up or down, no
atmosphere of varying temperature and humidity below ; whatever
the reduction is calculated to be, it can only vary with the pressure ;
the temperature correction has already been applied to the column of
air above the station ; consequently the conditions are very much
- simplified.

The formula of La Place takes into consideration the mean tem-
perature of the column of air below the station, but this is not always
so easy to find. The actual mean is not always the mean of the two
stations. The temperature variable makes a great difference in the
reduced reading, and is often very misleading ; so much so was this
the case, that in the year 1872 the Chief Signal Officer in America
ceased to use this variable for high stations and substituted an annual
constant. But stil] at stations of from 2,000 to 5,000 feet in altitude,

260 A. G. Howard.— The Barometer: [Sept. 28,

the same trouble was experienced by using the temperature variable,
and in the year 1881 a system for all stations was introduced, by
using monthly constants of reduction to sea level based on monthly
normal pressures and temperatures, but this has features quite as
objectionable as any other mode.

At the third meeting of the International Meteorological Committee
held at Paris in 1885, the late General Hazen of the American Signal
Service submitted a scheme for the reduction to sea level, by using
for the temperature variable, the mean of the observed temperature
and those of the two preceding observations where tri-daily obser~
vations are taken, and where only one observation a day is telegraphed
to send the mean of the hours 7, 2,.2and9. The idea as far as b
can see is to use the progressive mean of the day. Mr. Leyst*
pointed out the error of this mode of reduction, which instead of-
obliterating the diurnal curve increased and misplaced it. He still
considers that the formula of La Place should be adhered to, and the:
constants and variables revised according to the light of moderm
science, and furthermore that the formula should be critically examined:
with a view to constructing tables to avoid the use of logarithms.
He professes to have solved this problem himself. This may be;
but I do not believe, even at the best, that it will be reliable for great
heights.

Riihlmann, who has corrected the formula of La Place, makes the
temperature answerable for all errors of reduction and alters his
constants accordingly. But this, I think, is not a very scientific
proceeding,

Leyst again points out that humidity has a considerable influence
on the pressure. So, I say, has the direction of currents, whether
they are rising or falling, The reductions in the centres of cyclones
and anti-cyclones would be totally different.

Latitude also makes a difference. According to Leyst; at an
altitude of 6,500 feet, a difference of 80° in latitude makes a difference
of -034 of an inch in the pressure. At the same altitude and with a
temperature of 20° centigrade, a difference in the relative humidity
of eighty-seven, causes a difference in pressure of ‘0638 of an inch.
Hence these factors are to be taken into account, and when we
consider that temperature and humidity vary considerably at different
heights, and that at a high station such variations are totally

* Pawlowsk Observatory.<

1887. | Its Reduction to Sea Level. 261

unnoticed, I fail to see that the formula of Leyst will be of greater
value than that of La Place. As I said before, the conditions are
totally different on elevated table lands, and it is principally to these
I shall devote my paper.

No formula will ever be reliable for mountain stations higher than
2,000 feet, and for these La Place’s as corrected is, and always will be,-
the best.

In reducing to a datum, it is not absolutely necessary to use the sea
level, almost any horizontal plane can be used, and the readings
reduced either up or down to it.

But there is a great difference in the results to be obtained by the two
modes of reduction. By reducing up we obtain a chart cutting through
various conditions of atmosphere, owing to the datum plane being at
varying heights above the ground ; at some points it will touch the
ground, and at others, be at varying distances above, 500 feet, 600
feet, or 5,000 feet or more.

Consider the varying conditions of the atmosphere at these different
heights.

I mentioned ina former paper that the storm-bearing stratum of
the atmosphere flows up and over the land where the slope is gradual,
but flows round mountain peaks ; so that over the Colony, the height
of this stratum would be approximately the same at Cape Town and
at Kimberley. Now consider this stratum to be 3,000 feet thick, and
let us assume it is very dense, while above flows a current of warm
air. A chart plotted on the plane of Kimberley would not represent
the actual condition of the atmosphere if reduced up from surface
temperatures. ,

Upon a chart reduced to sea level, the pressure at Kimberley is
least, consequently the gradient is from Cape Town and the wind is:
south-west.

But by reducing up to the plane of Kimberley 4,042 feet above sea
-level, using the surface temperature, minus the diminution for 2,021
feet, the reduced pressure would be much too low, the gradient being
from Kimberley, so that the wind would be shewn to flow to a high:
area instead of to a low. This will be better understood if we |
consider the temperature at Cape Town and Kimberley to be 602.
The correction reduced down for Kimberley would be with a variable
of 67°, but for Cape Town reduced up it would be 58° or a difference
of 14°, causing a difference in pressure of ‘090 of an inch. Thus if by
reducing down Cape Town reads 30°05 inches and Kimberley 80°00

“262 A. G. Heward.— The Barometer: [ Sept. 28,

inches, by reducing up Cape Town will read 25°94 inches, and
Kimberley 25°98 inches, thus reversing the gradient.

In reducing down to the sea level the conditions are totally different.
It is true that this is an attempt to delineate an impossibility, but of
the two impossibilities it is the least objectionable.

If we assume the whole of the solid earth above the mean sea level
to be so much atmosphere, perfectly tranquil and unaffected by
temperature, currents or any movement, and in layers of diminishing
density, the atmosphere itself rolling over it as it does over the solid
earth. If we again assume that the weight of the atmosphere above
this mass affects it by compression, so that the surface pressure shall
bear a proportional ratio to that, at the sea level, we have data for
-constructing reduction tables, for varying heights, provided we know
the decreasing ratio of atmospheric density.

It has been demonstrated that the density of the atmosphere
decreases with the squares of the distances, and that the number
representing this decrease of density obtained by dividing the pressure
at any altitude into 30 inches, increases in the proportion of the power
of the quotient of altitudes, or in other words, if B represents the

upper pressure then log. = increases directly as the altitude, so

‘that by applying a correction to the height, -the log. of = will be

- obtained.
Hence we have the resolvable equation—
30
SS ib 1
5 9 Q)
Where H is the altitude in feet, and B the pressure at that altitude,
-# is a constant and g the latitude correction.

To find k, let a represent log. = Then, omitting g we have,

H = log.

-ak = H, and consequently —
k= H (2)

a

So that by taking the mean of a number of readings at two
stations, the one at sea level and the other at a known altitude, we
‘ean easily work out &. I have calculated this from readings at
\Graham’s Town and Port Alfred, and find it to be 65,000. This
number varies slightly with the sea-level pressure, varying from
64,900 to 65,100, from a pressure of 29 to 30 inches. It is also the
same for all altitudes. .

1887. | Its Reduction to Sea Level. 263.

The latitule correction has now to be considered. The weight
of a body on the earth, decreases from the poles towards the equator in

2
the proportion of W (: — ~~ so that the weight of the atmosphere.

below any altitude, or the term 380 — B will increase in that propor--

tion towards the poles, hence the latitude must be replaced by the

co-latitude, and as the cosine of the co-latitude is the same as the

sine of the latitude, we have the latitude correction as 1+°00346-.

sin’¢. Colonel Clarke from pendulum observations has altered the-
co-efficient to ‘002606.

The formula for heights based on the foregeing is

H = 65,000 (1 — '002606 sin79) log. = (3)

and for reduction
BH (1 + :002606 sin’9)
08: 65,000 (4)

The reduction to the gravity of latitude 45° is given by La Place
as 1+ °00284 cos 29.* Professor Archibald, from Colonel Clarke’s
observations, has altered this to 1 — °002606 cos 29.

Between Cape Town and Kimberley this correction for gravity

makes a difference of ‘013 of an inch, so that the reduced readings
at the latter shou‘d have this correction applied subtractively.

The foregoing gives the argument upon which I have considered
this question. Of course the formula given will only be applicable
for stations on elevated plateaus. For mountain stations they will
not answer, as temperature and humidity have such different effects
at such stations to what they have on elevated table lands. More-
over the atmosphere between the station and the foot of the mountain
has to be taken into consideration with all its varying conditions.
For these stations I would introduce the temperature correction

e=t+ 5 where ¢ represents the mean temperature of the date
c

of observation for a great number of years, and B. the variation due
: Cc

to altitude, c being the number of feet in which the temperature de-
creases one degree. This variable c is different for different latitudes
and temperatures.

In the tropics the perpetual snow limit is 16,000 feet above the sea
level. Taking this as a datum we find that with a sea level tempera-
ture of 80°, the decrease is 1° in every 333 feet of altitude, but with a

* Co-Latitude.

264 A, G. Howard.— The Barometer : [ Sept. 28,

sea-level temperature of 60° the decrease is 1° in every 571 feet. The
height of the limit of perpetual snow decreases towards the poles in
the proportion of the squares of the cosines, and the altitude wherein
the temperature decreases 1° will vary accordingly.

By the term tropic I mean that parallel of latitude where the sun
shines vertical. The calculation for decrease must be made from this
parallel and not from the equator, bearing in mind that solar action
lags behind nearly a month. The decrease of temperature due to
altitude which I have mentioned is the mean decrease ; the nearer the
surface of the earth, the quicker does the change take place. This
question of decrease of temperature ought to be gone into practically,
and J should like to see it done here. We have Table Mountain and
Lion’s Head. Why not utilize them? A wet and dry bulb on
Signal Hill would help. Where there’s a will there’s a way, and I
should like to see South Africa take off the palm in this question,

T will now pass on to some practical results. My first attempt to
construct charts from barometer readings at high altitudes, was early
last year. I compiled thirteen charts for 1885, twelve monthly means
and a yearly one. I used Hazen’s tables of reduction, and was very
successful.

On attempting to plot daily charts, I found that temperature, which
had been reduced to a mean in the monthly ones, seriously affected
the reductions. One station had too high a reading, another too low,
consequent upon the height of the thermometer, and the greater the
altitude the greater the error. .

I was so annoyed at this, that 1 destroyed the whole of them, and
plotted new ones, using only those reductions for a temperature of 62°.
By these means the differences were done away with, and I came to the
conclusion that temperature had nothing to do with a formula for reduc-
tion on elevated plains. IJ then began to work out tables of my own.

The result of my work I now place before you. I do not assert it
is perfection, nor do I say the formula is new. A new formula is not
wanted. As I said before, mine is to be used solely in reducing from
table lands, and by using it we do away with the discrepancies due to
the temperature variable, and with the anomaly of a temperature
correction where no atmosphere exists.

I have compiled tables of my own for all the principal places in the
Colony from which returns are received, and have been successful so far.*

* Charts for the first six days of January and of July, 1885, were exhibited at the

meeting.

1887. ] Its Reduction to Sea Level. 265

In conclusion I will give two cases, to show how erroneous it is to
take temperature into consideration on elevated table lands. Assume
two stations ten miles apart, situated on a plain, both having the same
altitude and barometer reading, while the temperature of one is 10°
warmer than the other. Upona chart plotted on the plane of these
-stations both pressures would be alike, which is the truth, but upon
their being reduced to sea level they are totally different, which is an
untruth, but by my mode of reduction the truth would exist, even at
-the sea level.

The other case is this. Often when pressure has been very steady
-all over the Colony, the diurnal range of temperature at an elevated
station has heen very great. Now if the readings had to be reduced
to a steady sea level pressure the upper barometer must have oscillated
very much, but as such was not the case, the effect of temperature
must have been zl. Major Pinto, a traveller who crossed Africa from
Benguela to Natal, notices this. He says: “ Whoever bestows any
_attention upon the meteorological observations I publish, will see that
the atmospherical changes in this part of Africa have but a slight, if
any, influence upon the pressure, which remains the same amid the
most sudden variations.”

And again he says: “ An investigation of these tables will shew
-the great uniformity of the barometrical oscillations and the enormous
inequalities of temperature and humidity of the air in the countries to
which they refer.” The country Major Pinto refers to is the great
table land of Central Africa, far from all influences of atmosphere
below the places of observation.

ADOLPH G. HOWARD

Cape Town, 28th September, 1887.

ah ee
hte + 4, ¢ , f

\ *

pate.
Tae

ene a! alan buts

THE ACACIAS OF SOUTHERN AFRICA.
By R. Martrortnu, Pu.bD., M.A.
[READ 26TH OCTOBER, 1887. |

"THERE is scarcely any book on travel in Southern Africa that does
not contain some pages dedicated to the description of thorns and
‘spines on plants. Although most of our travellers took very little
interest in botany, they could hardly help paying considerable atten-
tion to a subject that was forcibly obtruded upon them every day.
In the coast districts of the Cape Colony and in the regions extending
towards the north-east spiny bushes or trees take a less prominent
place in the vegetation of the country, and those armed with such
weapons belong to several very different families. In the central
regions however and especially in those vast tracts which extend
north of the Orange River far beyond the tropic of Capricorn, one
family, or to speak more properly one genus, of thorny trees comes
to the front and impresses its character on the landscape. This is
the genus Acacia. ‘Two species of acacias are familiar to all of us,
namely the common Karroo-thorn and the so-called Port Jackson
willow. The latter is not indigenous to this country, but comes from
Australia, and { may here mention, that the large genus acacia, which
-contains over 400 species, is distributed over three continents:
Australia, Africa and America. On our continent it is principally
found in the northern and southern countries ; but our number of
species is much inferior to that of Australia. The Port Jackson
willow being a typical representative of the bulk of the Australian
-acacias, and the Karroo-thorn one of ours, the difference between
the two branches of the genus is apparent.

There are nineteen species known from South Africa, six of which
belong to the eastern coast districts, namely: A. arabica, natalitia, |
raffra, spinoza, Kraussiana, pennata, whilst three have been found
only in the eastern Transvaal: A. ferax, Burke and eriadenia. One
species only, the above-mentioned Karroo-thorn, reaches our neigh-
‘bourhood, the remaining nine species being restricted to the Kalahari
region, where I collected them all but one. To these must be added
seven new species which I discovered in Damaraland, namely: A.

hereroensis, Engler ; A, trispinosa, Marloth et Engler; A. dulcis,
K

DER — ki R. Marloth, Ph.D., M.A.—The [Oct. 26,.

Marléth et Exgler ; A, Luderitzu, Engler; A. Marlothii, Engler ;-

A, uncinata, Engler ; A. ————— Engler and one new species from
Griqualand West. These twenty-seven species are easily arranged
in two natural groups according to their inflorescence, the one section
bearing the flowers in glameroles, the other one in racemes.

Less scientific, although perhaps sufficient from a practical point-

of view, is the principle of classification which Baines* mentions as
established by Dr. Kirk. He divides them into three groups, viz.,
species which tear the clothes, those which tear the flesh and those
which tear clothes and flesh.

For our purpose, however, I thought it best to adopt another plan

and to deal firstly with the shrubby species and then with the trees,
putting aside the two climbers (A. pennata and Kraussiana).

There are altogether fifteen species of the shrubby form, out of

which number I may mention the seven most remarkable types.

A. stolanifera, Burch., the lowest of all of them, is common in
Griqualand West. The branched underground stem sends up
numerous straight twigs, 3 to 4 feet high, which, growing close

together, form pretty little islands of fresh verdure on the rufous soil.

A much greater influence on the features of the country is exerted
by A. detineus Burch., the Haakedorn of the colonists. Itis a bush
6 to 10 feet high, sometimes forming thickets to the exclusion of all

other shrubs. Such places are very trying to the traveller and parti-

cularly so to his oxen and the canvas-cover of his wagon. I cannot
better illustrate this obtrusive plant than by quoting Burchell,t who
named it detimeus out of mere revenge. He made his first acquaint-
ance with it shcrtly after he had passed the Orange River and he
describes this interview as follows :

“TI kept with two of the Hottentot waggons, but they led me

through such close thickets of thorny bushes, and which seemed ready |

every minute to tear away the canvas from the tilts, and our clothes
from off our backs, that I had given up all hopes of finding our way
out of them till the morning. . . . The largest shrubs were about
5 feet high. . . ., and it is the same thorny bush which gave us

so much annoyance the night before where it was above 7 feet high.

I was preparing to cut some specimens of it ; which the Hottentots
observing, warned me to be very careful in doing so, otherwise I

should certainly be caught fast in its branches. In consequence of

* Th. Baines. Explorations in South Africa, p. 147.

TOW. 5, Burchell, Travels in the Interior of Southern Africa Vol. J., pp. 308 and
809. London, 1822.

1887. ] Acacias of Southern Africa. 269

this advice, I proceeded with the utmost caution, but, with all my care,
a small twig caught hoid of one sleeve. While thinking to disengage
it quietly with the other hand, both arms were seized by these
rapacious thorns, and the more I tried to extricate myself, the more
entangled I became ; till at last it seized hold of the hat also ; and
convinced me that there was no possibility for me to free myself, but
by main force and at the expense of tearing all my clothes. I there-
fore called out for help, and two of my men came and released me by
cutting off the branches by which I was held. In revenge for this
ill-treatment, I determined to give to the tree a name which should
serve to caution future travellers against allowing themselves to
venture within its clutches.”

I found a larger variety of this species in Damaraland which forms
_there bushes often some 20 feet high.

A, trispinosa Marloth et Engler, a new species from Damaraland,
is a low bush, 3 to 6 feet high. I named it t¢rispinosa, on account of
it having three spines under éach leaf. As the specimens show, this
species possesses not only the two recurved hooks of the hookthorn,
but also a third one between these two, which is bent in the opposite
direction. It is a pity that Burchell did not make the acquaintance of
this bush, for he would have certainly supplied us with a graphic
account of the superiority of such an arrangement over the simple
system of hooks on the hookthorn.

Another new species from Damaraland is A. dulcis Marloth et
Engler. It forms bushes of nearly the same dimensions as the
Damaraland variety of the hookthorn, but it is easily recognized by
its white or reddish-white bark. It is remarkable for its producing a
gum, which is quite different from the common acacia-gum, being
sweet and eatable, so that it serves as a regular sweet-meat to the
natives. Hence the name dulcis.

A, haematosylon Willd. forms shrubs or little trees, 5 to 10 feet
high. Burchell found it near Griquatown, since which time it has
not been recorded. I saw it in the neighbourhood of Kuruman. It
differs from all the uther species by its slender and elastic branches,
drooping like a weeping willow.

A. Oaffra Willd. a native shrub of the Eastern districts may be
mentioned, not on account of its weapons, which are comparatively
small, but for its much larger leaves.

As the last member of this series I have to mention another new
species from Damaraland, which I had named inermzs, on account of

its having no spines or prickles whatever, but the name of which has
K2

270 R. Marloth, Ph.D., M.A.—The [ Oct. 26,

been changed by Prof. Engler to that of A. Marlothii. Amongst all
the South African species this is the only one which is unarmed.

There are eight species of acacias growing to the size of consider-
able trees.

I mentioned already the common Karroo-thorn (A. horrida Willd.),
which abounds on the banks of rivers and water-courses in the coun-
tries east and north of us. It forms beautiful groves ; for instance, on
the banks of the Orange River, as may be seen from the charming
painting in Burecnell’s book above quoted. It does not, however,
always grow in such clumrs of slender stems. In the Eastern
Province, for instance near King William’s Town, numerous isolated
trees stand on the slopes of the hills, reaching a height of 20 to 30
feet, and in Damaraland I saw trees 50 feet high. Its name horrida
has not been given without sufficient reason. The geminose spines,
as white as ivory and often as long as a finger, are as sharp and
pointed as a needle. Hence the branches of this acacia are very
welcome to the traveller when he is obliged to erect a kiaal for his
cattle, for even the roaring of a lion will not terrify his oxen to such
an extent that they would break through a fence of this kind.

Another species, A. hebeclada De., is also of a very variable size.
Generally occurring only as a shrub, a few feet or vards bigh, it forms
on more favourable places considerable trees with a trunk as thick
asaman’s body. This species, I think, boasts of more formidable ~
weapons than any other one, for its strong and sharp hooks are often
an inch long, and, being covered with a fine tomentum, not only
lacerate the flesh, but produce a very painful itching, which lasts
long after the wound has been inflicted.

Straight spines and recurved hooks are combined on another
acacia, which Burchell named appropriately A. heteracantha, although
there are several other species armed in the same manner. There is,
however, no specimen known which with safety can be referred to
this name. I thought first that a species pretty common in Griqua-
land West should be considered to be Burchell’s A. heteracantha, but
the shape of its legumes differs so widely from B.’s description, that it
has been necessary to give it another name (A. spirocarpoides Engler).
It is only 15 to 20 feet high, but another species, similar in its external
appearance and differing also by its legumes (A. Maras Engler),
grows to a lofty tree of 40 to 50 feet, adorning the valleys of Damara-
land. These three species are, as I suppose, the Hauk en steek of the
Dutch colonist, for the long spines prick the unfortunate victim which
the hooks prevent from escaping.

TSS.) Acacias of Southern Africa. 271

The most important South African representative of this genus is
the camelthorn, which name, however, is applied to two nearly allied
species, the A. Giraffae of Burchell and the A. eriolada of Meyer.
The first one, the Mokdala of the Betchuanas, was formerly common
enough in the Free State, Transvaal and Bechuanaland, the other
one, the Omumbonde of the Hereros, takes the place of the former in
the western parts of the Kalahari region. I said, that the Mokdala
was formerly common in the countries north of the Great River, but
it is notso any more. For more than fifteen years all the steam-
boilers of the Diamond Fields have been heated with its wood, which
almost equals coal in respect to its heating power, and it is therefore
not surprising that this tree has nearly disappeared from the country
within several hundred miles round Kimberley. Before the com-
pletion of the railway to Kimberley, thirty to forty wagon-loads of
this wood were brought to market every day, which amonnts to a
yearly consumption of 5,000 tons. The wholesale destruction of the
Mokdala in a country which is almost deficient in other trees of
remarkable size is very much to be regretted, for it has considerably
increased the dreariness and monotony of these regions. A _ full
grown Mokaala is a beautiful tree. It is not often over thirty-five
feet in height, but the thick trunk, two or three feet in diameter, bears
an umbrella-shaped crown, resembling thus in the distance the
famous stone-pine of Italian and Greek landscapes. In former times
hills and plains of those vast northern territories were adorned with
scattered Mokaalas and the sun-burnt traveller could pull up his wagon
under its shady roof, but now, having once left the willow-fringed
banks of the Orange and Vaal rivers, he may pass along for many a
day without perceiving a single tree rising above the shrubs of the
hookthorn and vaalbosch (Tarchonanthus minor Burch.).

The other camelthorn, the Omumbonde, reaches the same dimen-
sions as the Mokdala, but it never assumes such picturesque form
having more resemblance to an old knobby oak.

Both trees differ from all other acacias in the shape and size of
their pods.

The last acacia which I intend to deal with here is the Ana-tree.
(A, albida Del.). It is not a South African species properly speaking,,
occurring principally in Western Central Africa and in the regions.
of the Upper Nile, but it comes within our limits on the northern
border of Great Namaqualand. It is the pviggest of all our acacias,
having a trunk often four feet in diameter and a height of sixty feet.
The large crown is generally hemispherical with fresh, rich foliage,

Die R. Marloth, Ph.D., M.A.—The [ Oct. 26,

and such trees, which abound along the river beds of those countries,
afford therefore much better shelter against the sun than any other
species.

The legumes of the ana-tree are broad, twisted, and not leathery
as are those of the other acacias. They are farinaceous and constitute
a very valuable food to herbiverous animals. This is probably one
of the reasons for the comparatively wide distribution of the ana-tree?
for the hard seeds pass undigested through the animals which have
fed on its pods.

Having become acquainted with the principal representatives of
this genus, it will be of some interest for us to throw a retrospectiv®
glance on the various forms we have met with. We have seen some
species which are only a couple of feet high and others which raise
their lofty heads high above any other indigenous tree. We have
admired the rich foliage of the ana-tree and looked almost with pity
at the few poor leaves of the hookthorn. We found a greater variety
still in the formation of the pods and spines. The pods are of all
shapes and sizes; linear, moni'iform, oval or half-moon shaped ;
straight, bent, sickle-shaped or twisted ; thin and papery, leathery,
woody or mealy, and from one inch to six inches long.

Fir spines, or in some cases the prickles, are straight or recurved,
or both kinds are combined on the same branch ; they are short or
long, thin or thick, glabrous or pubescent, rigid or elastic. They
oecur mostly in pairs, one species however having three under each
leaf and one species only being entirely destitute of them.

The question arises: What are the causes of such variety of
forms in a comparatively small number of species? Or since our
knowledge of the matter at present is not sufficient to enable us to
grapple with the whole of such a complicated problem, we may
at least ask: Can any relation be shown to exist between certain
peculiarities of these plants and their surroundings, especially as
far as climate, rainfall, soil, etc., are concerned ?

We are accustomed to find the larger forms of nearly allied plants
in localities which have an ampler supply of water, but this common
rule does not hold good in this case, as a comparison between the
Karroo-thorn for instance and the camelthorn shows. The former
although growing on the banks of perennially flowing rivers, is much
inferior in its dimensions to the latter, which prefers dry plains and
stony hills.

“Tt is surprising,” says Grisebach in his book Die Vegetation der
Erde, “that such a delicate thing as the acacia-leaf is able to exist

1887. | Acacias of Southern Africa. 273

-under the scorching sun of the desert, where all the other bushes
bear thick and leathery leaves.”

There can be no doubt that the acacia-leaf does possess some
~means of protection against the detrimental effects of heat and sun,
and we find on examining the different species with regard to this
point, that the leaves are the very organs where adaptation to
circumstances has reached a high degree of perfection. We have
already seen how economical for instance the common hookthorn
is in the production of leaves as compared with other species of
moister situations, but it is not so much the quantity of the foliage
as the structure of the leaves, which enatle them to exist under
such trying conditions.

Almost all the acacias, and especially those which inhabit the
desert-regions, contain in their sap a certain amount of gum and
the juice of their leaves is more viscid and less watery than that
of other plants. It is obvious that this peculiarity of the leaf tends
to lessen the loss of moisture, for a slimy, gummy, fluid evaporates
more slowly than an aqueous one.

Another very effective arrangement for the protection of the leaf
is its periodical motion. In the morning the leaflets open and stand
out almost horizontally, but towards 10 or 11 o’clock, when the
insolating heat of the sun becomes more intense, the leaflets rise
towards their rachis until the two upper sides of each pair touch
each other. The twofold advantage gained by this change of position
is apparent. The leaflets, turning their edges towards the sun
instead of the broad surfaces, are thus enabled to avoid the direct
effect of the sun’s rays and as each pair then exposes only two sides
to the hot air instead of four, their transpiration must be less than
in the former position. In the afternoon, when the greatest heat
has passed, the leaves open a second time, closing again about sunset
on account of the cooler night. In A. destineus this arrangement is
s0 perfect, that even large bushes throw almost no shade in the
middle of the day and there is nearly as much sunshine under such:
a bush as at the side of it.

The most striking difference, however, between the species which
grow in dry localities and those which are only found where subter-
ranean water is present, is to be observed in the anatomical structure
of their leaves. Taking again for comparison the karroo-thorn and
the camelthorn and examining transverse sections of their leaflets
under the microscope we find that the tissue of the former is formed
of large cells with considerable intercellular spaces, and that the

274 R. Marloth, Ph.D... M.A.—The Acacias of Southern Africa.

epidermis consists of comparatively large cells with thin outer-walls,-
but in the latter the cells of the tissue close tightly together and the-
cells of the epidermis are provided with a very thick outer-wall..
This wall measures in the former case only 3 to 5 p, but in the latter
15 to 18 ». The Karroo-thorn like the ana-tree grows only along the
rivers, or at least on such spots where underground water exists, and
they can therefore well afford to lose a considerable amount of mois-
ture by transpiration, but the inhabitants of dry hills or plains, such
as the camelthorn and the hook-thorn for instance, must economize
the precious liquid and prevent its loss by all available means.

But it is not only against the climate that the acacia-leaf must be-
protected.

What purpose, the inquisitive observer of nature will ask, is served
hy all these nasty spines and prickles, which appear to be there only
to worry the traveller? The answer to that question is not far to
seek. Linnzeus already called the thorns the weapons of the plants,
and it strikes us at once, that the spines and hooks of the acacias
protect their leaves against the attacks of grazing animals. In a
desert like the Kalahari where no blade of grass can exist for many
months ‘of every year, whilst the country often teems with large
game, the delicate leaves of the acacias would be completely destroyed
year after year were they not so well protected.

I have made an interesting observation bearing on this question.
Young bushes of the karroo-thorn as well as of the camelthorn
possess always the longest and most numerous spines, whilst those of
older and higher bushes are reduced in size and number. Young
twigs of the camelthorn for instance bear spines about two inches
long, but on older trees they seldom reach half an inch. As long
as the bush is low its leaves must ve well protected, but once grown
to sufficient height it is no longer exposed to the attacks of game, and
the material which is not required for the construction of spines can be
employed for other purposes, as for instance, for the production of fruit.

These relations between the acacias of South Africa and their
surroundings remind us that if we desire to understand the pecu-
liarities of the vegetation of a country we must study, not only the
floral characters of the plants, but also their biology, for the members
of the vegetable kingdom are as well adapt ed to the peculiar require-
ments of the position which they occupy as animals to theirs. I
think it is apparent even from the few observations which I have men-
tioned above, that this group of plants serves remarkably well to-

illustrate this natural law.

ON THE SUBJECTIVE CAUSES OF EVOLUTION AS-
ILLUSTRATED BY THE GEOGRAPHICAL DISTRI--
BUTION OF PLANTS.

By Proressor GutTHRIE, LL.B.
[READ 25th APRIL, 1888. ]

ENE ROD We Tre Ni

WHEN a seed germinates the character of the plant that will be
evolved depends both on the nature of the seed and on its environment..

The first may be called the subjective, the latter the objective cause
of the plant’s ultimate form.

Soil, moisture, light, temperature, as well as man’s direct inter--
ference in training and pruning, may make all the difference between
a stunted pot plant of a few inches high anda magnificent forest
tree. But whatever differences may thus be objectively produced
there are certain unchangeable subjective characteristics due to the
nature of the seed itself which cannot be altered. No cultivation
for example will evolve a fir tree from an acorn.

It is now generally believed, and will here be assumed, that existing
species of plants and animals have been evolved from dissimilar
pre-existing species, and the question arises to what extent the forms
of existing species are due to subjective as well as objective causes,
that is to say to what extent the forms of existing species are due
to the subjective tendency or capability of the ancestral species from -
which they have been evolved of varying in what may be called
prescribed ways, or whether there is no such prescribed capability
or tendency and whether evolution is due to environment only.

Darwin’s theory of evolution by natural selection seems to have
left this question open. His own views seem to have undergone a
change between the dates of the publication of the first and last.
edition of the “Origin of Species.” At the date of his first edition
(1859) he seems to. have been disposed to account for evolution almost
entirely on objective grounds, whereas at the date of his last edition .
(1886) he clearly laid more stress on subjective causes of evolution.

It is true that the only subjective element of evolution he expressly

2716 Prof. Guthrie, LL.B.— On the Subjective Causes of { April 25,

recognises is that of hereditary influence, but he does not seem to
deny the possibility of the existence of other subjective tendencies.

My object in the present paper is to enquire how far the geogra-
phical distribution of plants and other organisms on the earth’s surface
throws light on this question. With respect to the distribution of
plants the phenomena to be accounted for are as follows :

(1.) Large numbers of identical and of closely allied genera and
species of plants often extend over continuous areas possessing more
or less uniform physical conditions.

These areas are called Floral Areas. Schouw divides the surface
of the earth into twenty-five Floral areas, defining a Floral area
as being a region in which :

I. At least half the known species are endemic.

IJ. A fourth part of the genera are endemic or nearly so.

III. The orders are either peculiar to the region or have their
maximum there.

(2.) Identical and closely allied genera and species occur in widely
separated areas having similar physical conditions. Thus:

I. Two-thirds of the Antarctic genera and at least thirty species
are common to that region and Europe.

II. Between forty and fifty flowering species of Tierra del
Fuego are European. -

III. Half the genera of extra-tropical South America are
European.

IV. Half the genera of New Zealand are common to Europe.

V. Several so-called European species are found on the Austra-
lian Alps.

(3.) Regions very similar in climate and other physical conditions
have very different Floras : Thus:
I. North America and Europe.
II. Mexico, South Africa and Australia.
III. Tropical Africa, Tropical America and the Moluccas.
There are two theories to account for these facts :
(a.) The theory of local origin and migration.
(6.) The theory of simultaneous evolutionary development.

These two theories are not absolutely exclusive of each other, but —
they depend on somewhat different views as to the origin of species.

There are however certain common grounds of agreement which it
will be expedient first to mention.

1888. | Evolution as illustrated by the Geogr. Distrib. of Plants. 277

These are as follows .
(1.) There is no essential difference, but one of degree only,
between variety and species and between species and genus.
(2.) Existing specific forms ha ve in some way beeu evolved from
specifically different pre-existing forms.
.(3.) The process by which existing species have been evolved is
wholly or partially what Darwin has called “natural
selection’ (including in this term for convenience sexual
selection also).
‘The points in which the two theories differ are as follows :
(1.) According to the migration theory variations are due to
-environment only or to causes so obscure that they may conveniently
-be ascribed to chance. ‘They are all-round in character and almost
infinite in number, and there is no natural tendency or capability of
varying in any prescribed directions.
Similar variations may be produced simultaneously in different
-regions from similar environment, bat as the combinations of external
circumstances are practically infinite, as are likewise the possible
variations of the species, the chances of the same varieties and species
-beingevolved simultaneously and independently are infinitesimal.

The theory of simultaneous evolution on the other hand depends
-on the following hypothesis :
(2.) Variations, being correlative, are only possible in a compara-
tively limited number of directions and naturally tend to follow certain
lines, so that amidst circumstances not too dissimilar similar variations
will occur independently and simultaneously both in the different parts
-of the same area and even in the different areas over which a species
is diffused ; so that a varying species without any necessary inter-
-communication evolves throughout its area either the same or closely
allied species. |

According to the migration theory species originating locally have

become more or less widely disseminated by migration. The seat of the
- species being generally assumed to be the region in which the species
-and its congeners are most numerous. Going back to this region and
_applying the same theory, we have to conclude that the species now
- distributed over it originated in some limited locality, and continuing
the process the species is ultimately traced back either to a number of
individuals of the species somewhere simultaneously and independently
_. evolved, or to a single individual ancestor or pair of ancestors, from
~which all the individuals of the species have come by lineal descent.

278 Prof. Guthrie, LL.B.—On the Subjective Causes of [ April 25,

The former alternative however seems to be fatal to the migration
theory. If in any locality a number of individuals of a species A
simultaneously and independently vary either per saltum or by degrees,
and in the course of many generations into the B form, there seems
to be no valid reason why this process should be confined to one
locality of the seat or seats of the A species.

If independent simultaneous and similar variation be admitted at
all, it seems impossible to deny that it may take place in more than
one locality either in the same or different floral areas. The denial
of this possibility seems necessarily to involve the hypothesis of
species being derived from a single ancestor or ancestral pair.

On the migration theory the existence of the same species in remote
areas is accounted for either on the hypothesis of the actual con-
veyance of seeds or plants over the intervening regions by birds, ocean:
currents, or otherwise, or on the hypothesis favoured by Darwin and.
Hooker that the two regions where the common species exist were
once united with each other or at different times with some third
region by similar climatic and other conditions and thus formed a
single floral area, which has since become severed by change in the
climate and physical conditions of intermediate regions.

The existence of distinct floral areas under similar physical con--
ditions is not absolutely inconsistent with this theory of the origin
of species but presents many difficulties.

European species can and do thrive in America ; and vice versa, if
their migration on a large scale has been possible between Europe-
and the Antarctic regions, it is difficult to understand why there-
should not be a greater community of specific forms in regions so
close as Europe, and Northern Asia (which belongs to the European:
area) and America.

So also if migration were so efficient a factor in the distribution:
of species as this theory supposes it is hard to understand why so
marked a difference should still continue to exist in the fauna and
flora of islands belonging to the Moluccan and Australian areas,
which are only separated from each other by a narrow strait (see
Wallace).

A continuity of physical condition, such as would have connected
the Australian Alps and Siberia into one area, would surely have:
also connected the tropical and sub-tropical regions of Australia:
and the Moluccas and thus have left far more distinct traces of its.

existence.

1888.] Evolution as illustrated by the Geogr. Distrib. of Plants. 279

The theory of simultaneous variation accounts for the appearance
of the same species both over a continuous floral area and in widely
separated areas as follows :

From an ancestral species probably equally widely spread, having
everywhere a capability of varying in a limited number of directions
and a tendency to vary in still fewer, similar circumstances have over
some parts of the area favoured the production and survival here of

-one variety and there of another. The localities in which the same
varieties have been favoured, are not necessarily conterminous or
even in thesamearea. In other places again, circumstances not being

favourable to the new varieties, the species has disappeared.

The difference of the flora of regions similarly situated as far as
physical conditions are concerned would then be explained as follows :

Two areas, say Mexico and South Africa, have formerly been subject
-to different physical conditions and have thus developed different
specific and generic forms. Owing to change of circumstances the
physical conditions of these two regions have subsequently become
-assimilated to each other. ‘The conditions requisite for the same flora
are not then here present. Similar conditions operate on dissimilar
forms. In this way not identical but parallel species are produced,
resembling each other outwardly but not in the structure of the part
_on which classification depends. ‘Thus in Mexico we find the succulent
Cactaceze. in South Africa the suceulent Euphorbeacez.

The theory of the individual or dual origin of species on which
the migration theory rests, or rather, perhaps, on which the denial
.of the plurality of seats for the same species depends, seems to
be surrounded with difficulties.

According to this theory either the new species is produced per
_saltum or it is produced from a single line of ancestry which has
left no collateral issue.

Either hypothesis is inconsistent with the admitted prevalence of
-eross-fertilization.

If variations are all-round variations, following no perceptible law
_and selected by environment only, then where cross-fertilization is
the rule every attempt at variation would be swamped, or only those
new species would be produced which are self-fertilized, so that cross-
fertilization would either become unknown or very rare.

The production of new species per saltum is hardly worth serious
_consideration. In the case of all animals and dioecious plants it
-would involve the accidental and simultaneous production of two

280 Prof. Guthrie, LL.B.— On the Subjective Causes of | April 25, .

specifically identical individuals of opposite sexes and specifically -
differentiated from their ancestors, thus bringing us back practically to >
the abandoned doctrine of specific creations.

The individual or dual origin of species fails also in satisfactorily.
explaining the extinction of a varying species.

It seems to be generally held that existing species are collaterally, .
not lineally, related. Why this opinion is so generally entertained
is not very obvious. One reason perhaps is that species are not known
to sport into other species, which owing to atavism would sometimes -
be the case if existing species were related in the direct ancestral -
line. Now in the absence of a general tendency to variation on one-
or some few directions, this extinction of the ancestral form is not
easily accounted for. If a species diffused over a floral area gives -
rise to a variety in ove particular spot, in the absence of any tendency ~
towards the same variation elsewhere, it seems almost impossible:
that the new form should supersede the old. As Darwin has pointed
out, in order that a species may successfully invade a new region
it must not have any closely allied race to contend with.

Successful invaders of an occupied area to a great extent belong—
to genera not represented in the area they invade, and seldom or~
never do they belong to species closely allied to species existing
there. Still less is it likely that a variety formed in one area will
pursue and exterminate the parent species in an area now detached.
from that in which it originated.

Whatever theory is entertained as to the origin of new varieties.
must be also capable of explaining the disappearance of the form
from which it originated and in this respect the purely objective
theory of the production of new forms seems to fail.

According to the theory of variation in a comparatively few
directions due to an innate law or tendency, cross-fertilization is a
distinct aid to the production of new species and to the extinguish--
ment of the old.

Thus suppose a species A has a natural tendency to vary in a
direction which would ultimately produce a new species Z, and let the-
first step of variation produce the form B. Let A be an annual and_
let 20 per cent of its progeny take the B form.

Some few of these B’s may be cross-fertilized with each other, and
their inheriting the terdency to vary from both parents will leave-
progeny of which the majority will pass into the C form, another step-
towards the specific form Z. The great majority of the B’s, however,

\

1888. ] Evolution as illustrated by the Geogr. Distrib. of Plants. 281

will be cross-fertilized from A’s, and about an equal number of the A’s-
from the B’s. Of these inheriting on one side the B form and on the
other the tendency to the same form, the great majority will be of the B-
form, while of the A’s crossed with A’s, another 20 per cent will pass.
over to the B form. In this way it is obvious that the A form will
soon begin rapidly to give way to the B, and subsequent forms
tending nearer and nearer to X. We have here been supposing that
natural selection does not operate, and that external circumstances are-
equally favourable to A B and the subsequent forms up to X. _ If,.

however, this be not so, if natural selection favours the development

towards X, then the evolution of the X species and elimination of the:
A species wili be facilitated. If, however, natural selection be opposed
to the B variation, then the A form will simply tend to die out in its-
attempt to vary in a way in which it is not permitted to vary.

As this tendency to vary is supposed to characterize the species
wherever it exists, it is easy in this way to account for the compara--

tively rapid extinction of a species which is actively varying.

But it may be asked what proof have we of the existence of this.
capacity to vary in comparatively few directions and tendency to
vary in fewer still.

We cannot say that we have any distinct proof of the existence:
of such laws except in so far as these laws better explain the
evolution and extinction of species. Some arguments however may
be urged in their support : ©

(1.) The doctrine of the correlation of organic variation.

This doctrine is not to be confounded with that of the correlation
of organs.

‘Whatever be our theory as to the origin of species or the cause.
of variation, itis plain that no plant or animal could exist unless:
its organs were correlated not only with each other but with the
environment. Their eyes, teeth, limbs and digestive organs are
correlated with each other and the food supply. In order that
varieties may subsist they must involve the correlative variation of
the necessary organs. The harmony of life must be maintained...
Variations opposed to this harmony will be disadvantageous to the
individual. 3

The bare theory of casual variation with natural selection meets
this requirement by supposing that among the infinite varieties which
are always occurring those only will survive which involve the
requisite harmony with each other and the environment.

232 Prof. Guthrie, LL.B.— On the Subjective Causes of | April 25,

“Only give us sufficient time,” the casual evolutionist would say,
“and without requiring any law by which organic variations are
harmoniously correlated we can account for the fact that in the
outcome they are and must be so related.” This is true, but the
demand for time becomes excessive.

The correlation of variation of which we are now treating is
however something more than this. It is the law by which without
reference to natural selection, or the advantage of the individual, one
part of an organism cannot vary without involving the variation
of other parts also.

This subject has been so fully treated by Darwin that it is hardly
necessary to do more than to refer to his works on this subject.

Darwin has shewn that as both animal and vegetable forms, even
those most highly developed, consist to great extent of variously
developed homologous parts their parts must tend to vary corre-
latively to each other. Thus, for example, the jaws are related
to one of the three modified vertebrae, constituting the skull, in the
same way as the fore limbs are to another of these vertebrae and
the hind-limbs to one of the sacral vertebrae. Now Darwin points
out how breeders have noticed that these parts vary together, so
that elongated jaws are generally found with elongated limbs, both
fore and hind. Not only however do homologous parts vary together,
but the same is the case with respect to parts between which there
is no apparent homology, as in the oft-quoted case of white blue-
eyed cats being nearly always deaf, and tortoiseshell cats of the
female sex.

Again flowers and fruits are modified leaves. The varieties of
cultivated fruits have been produced by man’s selection with reference
to the fruit itself. Yet an experienced horticulturist can distinguish
the different varieties from the correlated and unintentional variations
of the foliage.

How far-reaching is this correlation of parts is well illustrated
by the fact that the experienced hologist can reconstruct the entire
animal from the fragment of a bone, can tell you not only that it
is a bird and not a mammal or reptile, but can tell you to what tribe
of birds it belongs, what was its size and its habits. So from a few
grains of tenui carbonized wood the phylologist will reconstruct
a tree with foliage, flower and fruit. :

(2.) The existence of a tendency to vary in certain directions with a
capacity of varying in others is well illustrated from the experience of
breeders of plants and animals.

1888.] Evolution as illustrated by the Geogr. Distrib. of Plants. 288

Man, selecting for his own purposes, has probably not succeeded in
producing a single new species of plant or animal, and probably not a
single naturally permanent variety which might be regarded as a step
towards a new species.

Unless kept under man’s incessant supervision our cultivated plants
and domestic animals revert to their ancestral form. Pigeons allowed
to breed freely among each other revert to the rock pigeon form, dogs
mongrelize towards the ‘‘ dingo ” type.

Not only is this the case, but in proportion as the varieties produced
by man’s selection deviate more and more from the parent type, so the
breed as a rule becomes increasingly difficult to keep up, on account of
increased delicacy of constitution and often also diminished fertility.

The explanation of this is that man tries to produce variations
which are not in the direction in which the spe@ies tends to vary, and
the further he proceeds with these variations, which we may call
_un-natural, the more difficult his task becomes. Not that variations.
occur less often, for the reverse is the case, but that the variant forms.
have not those qualities which ensure permanency in the ordinary
conditions of life.

Another experience of horticulturists also bears on the same point..

It is well known what difficulty there is to get some wild plants to.
vary when first taken into cultivation. Some have resisted for:
generations every attempt to produce desired varieties. At last some
lucky or more observant gardener detects in some individual a slight
tendency to vary in the desired way. Carefully separating this.
individual and breeding from it, he finds among some of its descendants.
a further variation in the required direction ; after this the task is.
comparatively easy. The descendants of those plants which for two or
three generations have varied in one direction vary freely, at first in
the same direction, and afterwards owing probably to corre.ation of
organs in other ways also. Thus illustrating the fact that the
tendency to variation is hereditary and produces like effects in many:
individuals.

(3.) Another observation tending to the same conclusion is the
frequent occurrence of well-marked varieties among wild plants
growing side by side with apparently identical environment, and the
fact that the same varieties also occur independently and in places
remote from each other with different environments. |

The collection and classification of marked varieties, especially

extreme varieties, sometimes called monstrosities, is at present occupy =
L

284 Prof. Guthrie, LL.B.—On the Subjective Causes of [ April 25,

ing many botanists, and the mere fact that such varieties can be and
are classified and named, seems to prove that vurieties are not all
round varieties due to chance (unknown law) but to definite laws,
which produce like results in places remote from each other.

(4.) The theory of a law of variation in predetermined directions
also renders more intelligible the development of organs so compli-
cated and specialized as the eye.

Darwin admits that when he reflected at what an early geological
period eyes of apparently perfect organization were produced, he
hesitated long to come to the conclusion that mere casual variation
and natural selection could have produced them.

The hypothesis of natural tendency to vary in prescribed directions
would remove much of this difficulty.

If we imagine that the early and lower forms of animal life were
sensitive to light over their entire surface, we can easily imagine
that the localization of this sensitiveness increased in degree, and its
suppression elsewhere might be an advantage to the animal. Such
a change being the first step toward the development of an eye if
occurring according to a law,a tendency to vary in a prescribed
direction might within a period, not inordinately prolonged, result in
the complete perfection of the orgun.

(5.) The migration theory supposes that man originated from a
single pair of ancestors belonging to some anthropomorphic species
now extinct, and that from this pair of ancestors, the Bushman and
the Caucasian have both descended. The theory of simultaneous
variation merely supposes that the Bushman and the Caucasian have
descended from the same ancestral anthropomorphic species but that
neither is the Bushman a degenerated Caucasian nor a Caucasian
an improved Bushman, nor that the Bushman and Caucasian descended
from common ancestors.

It may be urged against the theory of variation by common innate
tendency that it only accounts for the existence of widely spread
species by supposing the previous existence of an equally widespread
parent species.

This is true, but it is hardly a valid objection.

Geology in no very distinct terms perhaps, but still conclusively
enough, seems to tell us that the fauna and flora of the world
were formerly less diversified than at present: that species and
genera if not fewer in number were at least more cosmopolitan in
habit than at present: that for example the fauna and flora of

-1888.] Evolution as vllustrated by the Geogr. Distrib. of Plants. 285

Europe and America were more closely allied than is now the ease, that
the same was true of North and South America, and of Africa and India.
If this be granted we have no choice as to whether we are to trace
existing species to former equally widely diffused species. ‘The
problem is thus set as by nature itself. In passing from previous
geological times down to the present the phenomenon to be explained
is not so much why it is that some modern species are so widely
diffused, but why it is that modern species generally have become
relatively more localized, why for example the marsupials once
abounding elsewhere should now be almost confined to the Australian
_Area. Whether we adopt the theory of local origin and subsequent
»migration or that of simultaneous variation the main outlines of the
problem are in this respect the same.
It must be remembered that to advocate the doctrine of simultaneous
parallel variation as a cause of the co-existence of the same species in
-remote areas is not to deny that migration or accidental or intentional
transport is a cause also. Where the agency of man comes in, the
spread of species by migration is a well-known fact, and it is equally
well known that the spores of many plants and the seeds of not a few
can be carried great distances by the wind, that some seeds are trans-
ported thousands of miles by ocean currents, without losing their
vegetative powers, and that birds and even insects must sometimes
_transport seeds.
On the other hand too much stress must not be laid on the effect of
“the infinite variety of surrounding conditions or the differentiation of
nascent species. This variety is, it is true, in one sense infinite but in
another sense it is very limited. Climate, soil, and rivalry in the
struggle for existence may be varied infinitely but only in infinitely
small respects while in those general aspects which favour or oppose
_the success of a species, the variations are by no means so numerous,
. otherwise the same species would not sometimes flourish over such
large areas as they do, and in such vastly different conditions as to
soil, climate and competition, and would not be as capable as they are
-of rapidly overrunning new areas into which they have been acciden-
tally introduced.

DARWIN’S VIEWS.

Those who oppose the theory of simultaneous development seem to
-assume that they have the authority of Darwin on their side. This is

‘by no means clear. What Darwin’s opinions were on the points we
L2 ‘

286 Prof. Guthrie, LLL.B.— On the Subjective Causes of [ April 25,.

have been discussing are not so easily ascertained as might be sup-
posed, owing probably to the fact that Darwin’s views underwent a
change, which he himself admits, between the times of the publication
of the first and last edition of the Origin of Species.

I. Thus with respect to the descent of all individuals of the same
species from a single ancestor or pair of ancestors, we have the
following passages (sixth edition) :

(p. 820). . . . “Individuals of the same species.
must have proceeded from one spot where their parents were-
first produced.”

(p. 259) “If we bear in mind. . . . how often a species may
have ranged continuously over a wide area and then become
extinct in the intermediate tracts, the difficulty is not:
insuperable in believing that all the individuals of the same
species are derived from common parents.”

(p. 406) “ All individuals of the same species. . . . are
descended from common parents.”

On the other hand we have the following passage :

(p. 822). . . . “Individuals of the same species inhabiting”
the same area will be kept nearly uniform by intercrossing ;
so that many individuals will go on simultaneously changing,.
and the whole amount of modification at each stage will not be:
due to descent from a single parent.”

This last passage, though somewhat ambiguous, leaves us in some
doubt whether Darwin held that species are to be traced back to a.
single ancestor or ancestral couple, but they leave no doubt but that he-
was of opinion that each species originated in a single locality from
which it spread by migration. Nege |

II. On the closely allied point as to the existence in the individuals of

species of a tendency to parallel variations there is a somewhat
similar though less uncertainty as to Darwin’s final opinion.

Thus, on page 125, he heads a paragraph with the words :

Distinct species present analogous variations, so that a variety
of one species often assumes a character proper to an
allied species.

This he illustrates by the frequent occurrence in one breed of
domestic pigeons of a characteristic of another breed, but not found
among the aboriginal rock pigeons from which both have descended,.
as for example the occurrence of fourteen or sixteen tail feathers in:

-1888.] Evolution as illustrated by the Geogr. Distrib. of Plants, 287

the pouter, thus assimilating it in this respect to the fantail, and he
adds the words :

“YT presume that no one will doubt that all such analogous
variations are due to the several races of pigeons having
inherited from a common parent the same constitution and
tendency to variation, when acted on by similar unknown
influences.”

And after mentioning other instances of analogous variation he
goes on to add :

“ According to the agit view of each species having been
independently created we should have to attribute this
similarity . . . . not to the vera causa of commu-
nity of descent and a consequent tendency to vary in a
like manner, but to three separate yet closely related acts of
creation.”

Again on page 127 we find the passage :

“The difficulty of distinguishing variable species is largely due
to the aes mocking as it were other species of the
same genus ”’ :

~“ But the best evidence of analogous variation is afforded by
‘parts or organs which are generally constant in character,
but which occasionally vary so as to resemble in some
degree the sane part or organ in an allied species. I have
collected a long list of such cases.”

Now it is obvious that if the individuals of allied species shew
*this tendency to parallel variation such tendency must be far stronger
among individuals of the same species and still more among individuals
-of the same variety, and accordingly on page 91 Darwin says :

“The tendency to variability is itself hereditary, consequently
they” (ze. the individuals belonging to varieties of a
species) ‘“‘ will likewise tend to vary, and commonly in the
same manner as did their parents.”

‘These passages seem to prove almost conclusively that Darwin
“held that varying species have a tendency to vary in particular lines,
determined by those lines of variation which have evolved the species
itself.

On the other hand, however, there are passages in which Darwin
eseems explicitly to deny the existence of a general tendency to
-simultaneous variation.

288 Prof. Guthrie, LL.B.—On the Subjective Causes of [ April 25...

Thus on page 319 we read :

“There is no evidence, as was remarked in the last chapter, of |
the existence of any law of necessary development.”

And on page 291):

“These several facts accord well with our theory which includes
no fixed law of development, causing all the inhabitants of
an area to change abruptly or simultaneously, or to an
equal degree.”

If, however, these passages be carefully read with the context it
will appear that the law of development here denied is not one
affecting the individuals of particular species only but the individuals
of all species inhabiting a given area.

Nevertheless the following passage seems to shew that at the
time of the publication of the first and earlier editions Darwin believed
that species did originate from the casual variation of an individual,
and that it was only after the year 1867 that he came to the
conclusion that new permanent varieties and consequently new
species could only be formed by similar and simultaneous variation:
in many individuals of the same species.

In the IVth Chapter of the 6th edition, page 71, after illustrating
the action of natural selection by the example of the swiftest and
slimmest wolves alone being able under. certain circumstances to
subsist and propagate their race, he goes on to say :

“Tt should be observed that in the above illustration I speak
of the slimmest individual wolves, and not of any single:
strongly marked variation being preserved. In former
editions of this work I sometimes spoke as if the latter
alternative had frequently occurred” . . . “until reading
an able and valuable article in the North British Review 1867
I did not appreciate how. rarely single variations whether ~
slight or strongly marked could be perpetuated”

“Tt should not... . beoverlooked that certain rather strongly
marked variations, which no one would rank as mere
individual differences, frequently occur owing to a similar -
organization being similarly acted on.” :

“ Phere can be little doubt but that the tendency to vary in the
same manner has often been so strong that all the individuals
of the same species have been similarly modified without the~

aid of any form of selection.”

1888. ] Evolution as illustrated by the Geogr. Distrib. of Plants. 289

These passages would naturally lead to the conclusion that Darwin
originally believed that varieties and species originated from some
easual change in an individual, but subsequently came to the con-
clusion that varieties and species could only establish themselves by
the simultaneous like variations of many. There is however a
passage in the sixth edition of the “ Origin of Species,” which occurring
as it does in the final summary (p. 423) seems to render this conclusion
again somewhat doubtful.

Darwin is treating of the theory of the descent of organic life from
an individual primordial form.

““It has, he writes, been maintained by several authors that it is as
easy to believe in the creation of a million beings as of one,
but Maupertuis’ philosophical axiom of “ least action ”* leads
the mind more willingly to admit the smaller number ; and
certainly we ought not to believe that innumerable beings
within each great class have been created with plain but
deceptive marks of descent from a single parent.”

Here clearly Darwin regards the possession of similar characteristics
as conclusively proving descent from the same ancestor.

The balance of evidence seems, however, on the whole to be in
favour of the conclusion that as far as existing species are concerned,
Darwin held that they have been evolved subject to selection, by the
tendency among individuals of pre-existing species to simultaneous
variation in some limited number of directions determined by a
subjective cause which may be termed hereditary influence.

If then we recollect that Darwin held (p. 42) that wide-ranging,
much-diffused and common species vary most, it seems almost im-
possible to avoid the conclusion that according to Darwin’s tkeory
new variations in the same direction will occur over the area or in the
different areas over which the species is diffused and will develope
into like specific forms wherever surrounding circumstances are not
unfavourable, whether it be in one locality or many.

In confirmation of this view we may quote the following passage
(Origin of Species, p. 419) :

‘“¢ The existence of closely allied or representative species in any two
areas implies on the theory of descent with modification that
the same parent forms previously inhabited both areas, and
we almost invariably find that whenever many closely
allied species inhabit two areas some identical species are
common to both.”

290 Prof. Guthrie, LL.B.— On the Subjective Causes of | April 25,

Darwin himself explains this by supposing that of the identical
species formerly occupying these two areas, some have varied and
some have not, those which have varied being now allied species,
those which have not varied being identical species.

But as according to him widely diffused species are varying species,
it seems more in accordance with probability to hold that the closely
allied species are those which have varied from the common parent in
slightly different directions in the two areas, while the identical
species are those which have varied still more closely. At any rate it
seems impossible to deny that simultaneous parallel variation is a
vera causa for the existence of widely diffused species.

ORIGIN OF LIFE.

‘Let us now examine whether Darwin’s theory as to the origin of
srganic life on the earth throws any light on his views as to sub-
jective variational tendencies.

In the first edition of the “Origin of Species,” page 484, we find the
following passages : .

“I believe that animals have descended from at mast only four or

five progenitors, and plants from an equal or lesser number.”

“ T should infer from analogy that probably all the organic beings
which have ever lived on this earth have descended from
some one primordial form, into which life was first breathed.”

In the sixth edition, pages 424 and 425, similar passages occur, only
that for the second passage the words into which life was first
breathed are omitted.

Are we to understand from this that Darwin regarded the origin of
organic life on the earth as supernatural? If the words “ into
which life was first breathed ” which appear in the first edition seem
to imply the attribution of a supernatural origin to organic life,
their omission in the sixth edition might be regarded as showing a
desire on Darwin’s part not to commit himself to any such theory. On
the other hand, however, the following passage, also from the same
edition, seems to point to a different conclusion. On page 423 we
find the words :

“Tt has been maintained by several authors that it is as easy to

believe in the creation of a million beings as of one, but

Maupertuis’ philosophical axiom of ‘least action’ leads the
mind more willingly to admit the smaller number.”

1888.] Evolution as illustrated by the Geogr. Distrib. of Plants. 291

These words seem to be only consistent with the well-known
theological doctrine of “economy of miracles” and one would be
inclined to conclude from them that Darwin considered that origin of
organic life on the earth was supernatural.

The mere fact moreover of Darwin tracing back all organic life to
one or at the most a dozen primordial progenitors seems inconsistent
with any hypothesis but that of his believing in the supernatural
origin of life. If life originated from inorganic matter according to a
‘natural law it is quite incredible that this law in all earthly time and
“space should have operated ‘only once or even at most a dozen times.

Assuming then that Darwin regarded the origin of organic life on
the earth as supernatural, it is obviously in vain to look to his views
in this respect for any light it may throw on the origin of species.

But though Darwin’s views cannot assist us in this respect, it may
-be of some use to consider the subject on its own merits.

‘Setting aside the theory of supernatural origin of life, not as being
untrue or improbable but as putting the question out of the reach of
- scientific enquiry, there are three other hypotheses on this subject
~which seem worth consideration:

(1.) Organic life always existed on the earth.

(2.) Organic life came to the earth by migration.

(3.) Organic life originated and perhaps still continues to originate
- according to some natural law.

-Let us consider each of these hypotheses in turn.

(1.) Organic Life always existed on the Earth.

Against the first hypothesis it may be urged :

I. The perpetual existence of life on the Harth is inconceivable
Everything must have had a beginning, therefore organic life on the
Earth must have had a beginning.

II. The perpetual existence of organic life on the Earth is incon-
‘sistent with [a Place’s theory of the origin of our planetary system,
-according to which theory the Earth must at one time have been
in a physical condition inconsistent with the existence of organic life
in any form known to us or from which it is at all probable that
existing life would have been derived. |

4. To the first of these objections the reply is that the word
‘TInconceivable is here misused, No doubt the forms of things as we
observe them are always changing, and in this sense we are con-
strained to believe that all that exists is transitory. On the other
hand, however, we are equally constrained to believe in the continuity

292 Prof. Guthrie, LL.B.—On the Subjective Causes of [ April 25,.

of the present with the past, and we cannot realize a time when
nothing existed and something came out of this nothing. An infinite
period of vacuity ending with a creation is in the highest degree
incredible, and if we are precluded from ascribing a beginning to the
universe asa whole we cannot be compelled. to ascribe a beginning
to organic life either generally or on the Earth.

II. As to La Place’s theory it must be remembered that it is only
a theory, and that recent discoveries in Astronomy and Geology
have not rendered it more plausible.

Geology points to changes in the Earth’s temperature, but certainly’
not to continuous change in one direction. If in the Arctic regions:

there are indications of there having been a higher average tempera--

ture in certain remote geological periods, there are no less clear-
indications of a lower temperature having prevailed in regions
now temperate or even tropical. Geology moreover claims for the
formation of the Earth’s crust as known to us periods of time which,

the physicist arguing from La Place’s theory will not for a moment:

allow.

So also in Astronomy the observed motions of some of the Asteroids
and Satellites are admittedly at variance with the truth of La Place’s
theory.

On the whole therefore it would seem that the theory of the:
eternal existence of organic life on the Earth is not one that is.
to be summarily rejected as inconceivable or impossible, at the same-
time it is obvious that this theory is incapable of throwing any light

on the laws of evolution, as might indeed be concluded from the :

consideration that what we call infinite is negative or at least
privative and not positive.

(2.) Organic Life came to the Earth by Migration.

I. Some seem to think that this hypothesis is altogether unworthy
of consideration, and it must be admitted that it is very difficult to.
understand how any form of organic life that we are acquainted with
can have been brought to the earth from without. It would perhaps, .
however, be too much to say that such a thing is impossible, though we:
may safely conclude that if it has happened it is in the highest degree
improbable that it has happened only a few times. We are perhaps
too ready in placing the boundary of the possible at the limits of our
perceptions. We forget that in the minutest particle of meteoric dust:
there is, in a sense, as much room as there is in a planet, and that we
have not the least reason to suppose that organic forms are limited as.

1888. ] Evolution as illustrated by the Geogr. Distrib. of Plants. 293:

to size by the perceptions of our senses, even though aided by instru-
ments a million times more powerful than the best devised by man.
It is as well to remember that the abysses of the infinitely little are
really as profound as those of the infinitely great, that if our tele--
scopes reveal to us ever-increasing profoundities of distance, our
microscopes equally reveal to us the profoundities of minuteness, and-
in neither direction do we find trace nor can we conceive any
possibility of limit.

II. The migrationary hypothesis may likewise be objected to on
the ground that it merely removes the problem as to the origin of
organic forms to some other time and place. This is true, but the
hypothesis of the co-eternal existence of organic and inorganic forms
in the universe as a whole does seem to present fewer difficulties than
their co-eternal existence on the Earth. :

Moreover we are not now concerned with the relative probability of
the various hypotheses as to the origin of organic life, but with the
light which these hypotheses respectively throw on the theory of
subjective tendency to variation. Whether the migrationary hypo-
thesis is or is not satisfactory as to the origin of life, all we are
concerned about is whether this hypothesis suppeses the introduction
of life on the earth in one or only a few cases, or in an indefinite
number of cases, and it can hardly be denied that the latter is the

LAaSe.

(3.) Organic Life originated and perhaps still originates from Inorganic
Life according to some Natural Law of Continuity.

This hypothesis, sometimes called that of Spontaneous Generation:
is summarily rejected by some as being inconceivable. Here again:
the word inconceivable is wrongly used. There can be no difficulty
in the conception of continuity between what is called the organic
and the inorganic forms of matter, though there may be some
difficulty in believing that such continuity actually exists, since all]
our experience goes to shew that organic forms invariably proceed.
from previously existing organic forms. This difficulty would, how-
ever, be somewhat diminished by the reflection that our experience
imperfectly covers only an infinitesimal part of nature. Because
physicists have not yet consciously succeeded in producing organic
from inorganic forms in the glass bottles of their laboratories, it
by no means follows that in the wonderfully diversified conditions
which exist and have existed on the Earth, such production is

i

:
4
r 2
7

“294 Prof. Guthrie, LL.B.—On the Subjective Causes of Evolution, &c.

impossible. As already observed, in the boundless field of the infinitely
little there are infinite possibilities. The doctrine of spontaneous
generation has never been disproved, and probably never can be dis- —
proved, though the too hasty conc:usions of some physicists who have
claimed to produce the necessary conditions for the passage from the
inorganic to the organic forms have been successfully disproved.

To summarise these results, it may be said that the hypotheses of
the supernatural creation of organic life, or of its perpetual existence
on the Earth, throw no lght on its subsequent evolution, but the
hypotheses of the introduction of organic life by migration or spon-
taneous generation seem inevitably to lead to the conclusion that life
has originated on the Earth, not as Darwin supposes from one or a
.dozen ancestors, but that the process of life introduction is one that is
continually going ox, or at any rate must have happened a countless
number of times. Whether the forms of life thus introduced are
countless is another question. If it be permitted us to reason about
matter so entirely beyond our experience, we might infer from analogy
that the process of what may be called organic crystallization is
possible in only a limited number of ways so that the number of forms
produced by spontaneous generation, if such generation exists, would
be comparatively few. If the migration theory be true, then on the
other hand there would seem to be no limit to the number of forms
that might be introduced.

If the migration theory be maintained then the Darwinian
hypothesis may be sufficient by itself to account for the present state
of terrestrial organic life, since the immigrant forms may have brought
with them the hereditary tendency to vary in specific lines.

If, however, the doctrine of spontaneous generation be maintained,
then we seem compelled to supplement Darwin’s hereditary tendency
to specific variation by Lamark’s theory of a _ purely subjective
tendency to specific variations, supplemented by Darwin’s theory -as to
the objective control of such subjective tendency ; but, whether we
-accerpt Darwin’s theory alone or use it as a supplement to Lamark’s,
‘whether on account of heredity or on account of heredity and
‘subjective law combined, we are driven, to the conclusion that the
tendency is to variation in specific directions, and consequently to
the independent origination of the same varieties, and therefore of
the same species and genera, so that independent simultaneous
wariation must be admitted as a vera causa for the existence of wide-

spread species.

NOTE ON TEETH OF THE ZIPHIOID WHALE,
MESOPLODON LAYARDII (GRAY), EXHIBITED AT
THE MEETING OF THE SOUTH AFRICAN PHILO-.
SOPHICAL SOCIETY,

On WepneEspay, AuGuST 29, 1888,

By Rozranp Trimen, F.R.S., &.. CURATOR OF THE SOUTH
Arrican MusEUM.

As long ago as 1865, I made for my predecessor, Mr. EK. L. Layard,
outline drawings of the heads of two different species of Ziphioid
Whales then in the South African Museum; and he sent these
drawings to the late Dr. J. E. Gray, at that time Keeper of the
Zoological Department of the British Museum, who had bestowed
much study on the Cetacea. Dr. Gray determined the two whales
in question, merely from the drawings and Mr. Layard’s notes, to:
be both new species, and described them in the Proceedings of the
Zoological Society of London for 1865 respectively as Ziphius
Layardii and Petrorhynchus Capensis. The latter has since been
identified with Ziphius indicus, Van Beneden ; but the former (which
in the form and development of the teeth is by far the more remark-
able) retains its position as a very distinct species, peculiar, so far
as known, to Cape seas, and is placed by Prof. Flower (Trans. Zool.
Soc. Lond., 1872, vol. viii., p. 211) in Gervais’ genus Mesoplodon.
The Ziphioid Whales are most nearly related to the Cachalots
or Sperm Whales (as is shown in Prof. Flower’s memoir just quoted),
but, amongst other distinctions, differ temarkably in the very reduced
condition of their teeth, which (confined to the lower jaw) are
rudimentary and concealed in the gum, with the exception of one
pair (or oceasioually two pairs) at or towards the extremity. The
whales of this group were evidently numerous in Tertiary times,
as their abundant remains in the Crag formation testify ; but at the
present time they are certainly rare, only individual (usually stranded)
specimens now and then occurring in various parts of the world.
Mesoplodon Layardii exhibits an extraordinary development of
the only two teeth it possesses. They are situated at some little

296 Roland Trimen, F.R.S.—wNote on [ Aug. 29,

distance behind the apex of the mandible, are greatly compressed
laterally (so as to resemble a thick strap), and slant considerably
backward, while they are sufficiently long and curved inward
superiorly as to meet, or almost to meet, above the long and narrow
snout or beak. At the tip of each of these singular tusks there is
in front a conical compressed projection, looking like a small tooth
artificially inserted ; this Prof. Moseley (Votes by a Naturalist on the
“* Challenger,” 1879, p. 158) regards as the original small cap of
dentine of the tooth of the young animal, which, without increasing
in size, is carried up by the apparently abnormal growth of the fang,
the latter constituting the bulk of the tusk.

Both Mr. Layard and myself were at once struck with the obvious
difficulty that, if this singular position and form of the tusks were
not due to an individual aberration or monstrous growth, the case
-was one of a great mammal with its jaws naturally so locked together
as to be unable to open its mouth for more than a very little distance.
Both Dr. Gray and Professor Owen were inclined to look upon the
single original specimen as shewing merely an individual malfor-
mation; but, as Prof. Flower has recorded, Mr. Layard possessed
a single tooth of another individual having an exactly similar
conformation, and the discovery by Prof. Moseley (while here in
1873 on the Cruise of the “Challenger’’) of the lower jaw, with quite
similar tusks, of a third example rendered it almost indisputable that
the case was one of normal occurrence in this species. It is not
known whether, as Prof. Flower suggests, the tusks are peculiar
to the male animal. In connection with the difficulty referred to,
it occurred to me in 1865, when examining the type specimen, that
possibly the flattened tusks (which even in situ on the skull showed
some elasticity in yielding and separating when the lower jaw was
pressed downward) were to some extent movable at the will of the
animal ; and I have found, in the account by the late Sir Julius
Haast of the capture of an allied Ziphioid Whale (Berard:us Arnousi)
near Canterbury -in New Zealand, that an eye-witness of the dying
struggles of this stranded specimen observed ‘its front teeth to be
movable and protrusible. The food of these Cetaceans, as far as
ascertained, consists, both in the Northern and Southern hemispheres,
of Octopus and allied cuttle-fish ; and, if the mouth of Mesoplodon
Layardii is as closely locked by the over-arching tusks as it appears
to be, it is difficult to understand how it can capture these active and
watchful cephalopods.

ee

1888. ] Teeth of the Ziphioid Whale. 297

The tusks of this whale which I have brought for exhibition are
unquestionably a natural pair ; agreeing very exactly in size, outline,
and curvature. JI pur hased them for the South African Museum,
which since the original skull was sent to the British Museum, had
possessed no specimens representing the species. The only particulars
TI could obtain from the vendor as to their history were to the effect
that they were received for sale, among various other “ curios,” from
Knysna on the South Coast of the Colony.

- JT do not think that the actual locality of the type specimen is on
record. Prof. Moseley’s two examples were captured at Simon’s Bay
-and Walwich Bay respectively ; the former was stated to be about

10 feet in length, and the latter from 16 to 18 feet.

An animal of such rarity and such exceptional dentition, and
apparently peculiar to South African seas, is of great and special
‘interest ; and I trust that, by calling the attention of members of
the Society to what is known of the species, further specimens and
information may ere long be discovered.

298 C. Ray Woods.—On some [ Aug. 29,.

ON SOME PHOTOGRAPHS OF LIGHTNING FLASHES..
By C. Ray Woops.
[READ 29TH AUGUST, 1888. ]

Tue photographing of lightning flashes, it may be stated at the-
outset, is no new thing. Many successful photos of flashes have-
been obtained since the introduction of the Rapid Dry Plate Process -
now so universally used, and some of these, having come under the
notice of the Royal Meteorological Society, the Society deemed the
matter of so much importance that a Thunderstorm Committee was .
formed last year for the purpose of collecting and reporting on such.
photographs. Circulars were sent out inviting specimens, with a
request to all amateur and professional photographers to assist the
Committee. The process is simple. A camera focussed for long
distance objects is pointed in the direction whence the flashes pro--
ceed, the carrier slide is withdrawn and the lens uncovered for a time..
It is advisable to remain on the watch and cover the lens after the
appearance of a flash in the field of view, and then to expose a fresh
plate. A series of flashes on one plate, though it might make a more-
effective picture, would not lend itselfso readily to scientific investigation. .

On the evening of July 30th last, I took advantage of the thunder--
storm that then occurred to expose a series of plates. The most
open view from my residence is in the direction of the Cape Flats,
and in that direction bright flashes, or sparks, to use a better term,
were frequently appearing. Care was taken to get only one flash on
each plate, with the result that the larger proportion were failures, .
but on several plates I obtained images which I pass round. Though
inferior and disappointing compared with the others to which I draw
your attention, such as this photo obtained by Mr. Hawksworth in.
Natal, and particularly this fine photo obtained in Cape Town -by
Mr. Allis about a twelvemonth ago, they are of some interest, I
venture to hope, in elucidating and amending the report just issued by
the Thunderstorm Committee already referred to. I wish fparticu-
larly to draw attention to the fact that the sky was almost covered
with clouds of varying thickness ; this not only rendered some of the.

1888. | Photographs of Lightning Flashes. 299

«sparks too feeble to impress themselves on the plate, but cut off parts
of others, thinned their images in some places, and it may be assumed
‘with considerable certainty showed that the images that were obtained
were only such parts of the flashes or sparks as were visible through
-and between the cloud masses. Before referring to .their main
features let me draw attention briefly to the receut report of the
_Meteorological Society’s Committee, drawn up by the Hon. Ralph
_Abercromby.

The Committee reports that from the consideration of sixty photo-
graphs sent from Europe and America in answer to their circular, “ it
-is evident that lightning assumes various typical forms, under con-
. ditions which are at present unknown.” The following appear to be
- some of the most typical forms :

1. Stream Lightning, or a plain broad, rather smooth streak of
‘light. Only two or three specimens of this form were received by
the Committee.

2. “ Sinuous Lightning, when the flash keeps in some one general
direction, but the line is sinuous, bending from side to side in a very
irregular manner. This is by far the commonest type.” It is very
noticeable that the thickness of the line varies during the course of
discharge. Sometimes the thinnest part is the highest, at other times
_@ flash in the air begins thin, broadens out in the middle and thins
-again on approaching the earth. The Committee says that it can
offer no explanation of this at present, but draws attention to the fact
in some photographs of electric sparks taken from an induction
-coil, those of high tension are thinner than those of low tension.
This, I venture to think, affords no explanation of variation in
intensity during the course of one flash, though it may explain the
~wariation in thickness between two flashes.

3. Ramified Lightning, in which part of the flashes appears to
branch off from or run into the main streak like the fibres from the
root of a tree.

4, Meandering Lightning ; sometimes the flash appears to meander
- about in the air without any definite course and forms small irregular
loops. The thickness of the same flash may vary considerably in
-different parts of the course, as above mentioned.

5. Beaded or Chupletted Lightning ; sometimes a series of bright
-beads appear in the general white streak on the photograph. Occa-
sionally these brighter spots appear to coincide with bends in a

‘meandering type ; but often the beads appear without any evident
M

300 C. Ray Woods.—On some [ Aug. 29,.

looping of the flash. The Committee goes on to point out, what is
also plainly evident in the beaded appearance in the photographs
which I have taken myself, that it is evidently due to the flash taking
at times a course to and from the observer and giving a longer
exposure to these spots.

6. Ribbon Lightning. ‘“ Nearly one-sixth of the photos received by
the Society show flashes exhibiting more or less of a ribbonlike form.
One edge of the ribbon is usually much whiter and firmer than the
other.” The Committee points out that this form is probably due to -
double image formed by internal reflections of doublet lenses. This
defect then, if it is only a defect, is visible in my own photos, more
particularly in those parts of the flash nearest the edges of the plate...
My experiments were made with a doublet lens, as at the time they
were taken the report I quote was not published and I was not
aware that a sirgle lens gave the best results.

Of these various forms I pass round illustration and draw attention:
to the diagrams on the wall which are roughly copied from specimens
issued with the report.

The beaded appearance in my plates I have already drawn atten-—
tion to. Apart from this they might be classed as sinuous, meander-~
ing, or as ramified, as they partake more or less of all three
characters. I have already mentioned the clouded condition of the
sky and I need not add that clouds must necessarily be present where.
lightning discharges take place. The Committee have singularly
enough overlooked this, the simplest explanation of the variation in:
thickness of a flash. Cannot the cutting off of parts of a flash by”
cloud, and modification of the other parts of absorption through cloud, .
explain some of these forms assumed by lightning flashes ?

Let me draw your attention to two diagrams roughly copied from:
photographs of the electric spark taken by Mr. Trueman Wood, of the’
Society of Arts, with a large induction coil.

Here is a single spark which obviously corresponds with Class 1 or-
Stream Lightning. The next is the result of six successive sparks-
impressed on the plate. By covering portions of this photograph we-
can get tolerably near approaches to the sinuous, ramified, and.
meandering types. The beaded type, which is readily explained, has-
been obtained by Mr. Wimshurst with a large electrical influence.
machine.

In a thunderstorm, as terminals of the natural electric machine we-
have not one only but sometimes many points of discharge, in the-

1888. } Photographs of Lightning Flashes. 301

irregular form of the clouds, when it is from cloud to cloud,
and also when from cloud to earth, the earth may present various
points also, rather than simply one terminal. The discharge, whether
in many simultaneous or many successive sparks must necessarily be
very complicated, but still of the character shown by the six sparks in
the diagram. The masses of cloud obstructing parts of this com-
plication of sparks appear to my mind to afford sufficient explanation
of the various forms of lightning shown in the photographs.

To sum up. It appears probable then, that so far from lightning
assuming various forms under conditions at present unknown, it only
assumes two forms such as may be obtained in the laboratory,
the single spark and the eompound flash or series of sparks ; the
various forms of the latter being due to modification in appearance
by the obstruction of cloud masses. Bearing in mind that the former
view is put forward by one of our best living representatives of
Meteorological Science, I put forward a contrary wew with all
due diffidence, but in apology for my presumption I lay stress on the
fact that my own view is based on photographs taken by myself
coupled with personal observation of the condition of sky at the
time, whereas the view taken in the Meteorological Society’s report
is based on an examination of photos taken by others. In their
circular the Meteorological Society only asked for the photographs.
Had they ventured to ask photographers for particulars, were it only
a general description of the sky, though they might have found
fewer correspondents to communicate with them, I venture to think
that the Committee would have adopted views similar to my own.

Photographers in other parts of the Colony have better opportunities
of recording thunderstorm phenomena than we have here. If their
attention is drawn to the fact that by a little trouble on their part.
they may get results not only interesting in themselves, but of
importance in investigating phenomena which cannot be studied
without the use of the camera, they will doubtless join in furthering
the enquiry.

I may point out in conclusion that in no photos that have yet
been obtained do we get anything like the ridiculous conventional.
zigzags which artists represent in their pictures.

M2

302 C. Ray Woods.—On some Photographs, &c. [ Aug. 29,

SYNOPSIS.

1. Epitomised report of Thunderstorm Committee of Meteorological
Society of London on certain sixty lightning photos and their opinion
that lightning tends to assume various forms under conditions at
present unknown.

2. That the Meteorological Society have overlooked the modifying
influence of cloud in obstructing and absorbing parts of flash, although
it explains most simply one matter that puzzled them.

3. Enquiry whether the modifying influence of cloud cannot
also explain the various forms which the Meteorological Society
has classified.

4. The greater probability that lightning assumes only certain
forms which can be obtained under simple conditions in the laboratory
in contradistinction to the view put forward by the Meteorological

Society of London.

PHOTOGRAPHS OF LIGHTNING FLASHES TAKEN
SEPTEMBER 18, 1888.

By C. Ray Woops.

[READ 26TH SEPTEMBER, 1888. ]

At the meeting held here a month ago I brought forward some
attempts made to photograph lightning flashes during the thunder-
storm of July 30th. Ion that occasion drew attention to the report
issued by the Thunderstorm Committee of the Royal Meteorological
Society with various illustrations from the “ Photo News” and by
photographers in this Colony. A consideration of the various photos
of lightning flashes that had passed through my hands led me to
draw a different conclusion to that given in the report, which said
that there was reason to believe that “lightning assumes various
forms under conditions at present unknown.” The view that I
ventured to put forward was that the conditions did not greatly
differ from experiments in high tension electricity made in the
laboratory ; that it is more probable that lightning only assumes
two forms, the single spark and the compound flash or series of
sparks, the various forms of the latter being due to modification in
appearance only by the obstruction of cloud masses.

The photographs taken on the 18th do not tend in any way to
modify those views. Apart from the point brought forward in my
last part, I shall merely content myself with a brief description of
the photos. It would be interesting to speculate on the physical,
ehiefly electrical, conditions of this and the preceding storm, but
as any evidence that may be derived from these photos is too meagre
for any theorizing beyond vague suppositions, and unless any points
are brought forward in discussion to cause me to express any vague
ideas I may have formed thereon, I prefer to postpone the matter
till I can speak with greater confidence. By the time the next
thunderstorm occurs, I hope to be in a position to record it on a
more extensive scale.

304 W. Hammond Tooke.—The Star { Oct. 31,

THE STAR LORE OF THE SOUTH AFRICAN NATIVES.
By W. Hammonp Tooke.
[READ 31ST OCTOBER, 1888. |

Ir is with much diffidence that the writer places the following few
notes upon some of the conceptions held by the barbarous tribes
peopling South Africa respecting the heavenly bodies before the
members of this Society.

The facts are too few and fragmentary to justify any attempts to
formulate a theory on them, nor has any such attempt been made.
They are merely recorded here for the sake of comparison.

It may be held that they are not of any practical interest; but
such as they are, it is from these almost trivial data that powerful
side lights are sometimes thrown upon what would otherwise be
completely buried in the mists of obscurity, namely the unwritten
history of the races, some prolific, some nearing extermination, which
preceded the European occupation of taois continent. And they help
us to realise a mental condition which has much to teach us, both
by its resemblances to our own and by its dissimilarities.

“It is,” says Professor Drummond, “a wonderful thing to look
at this weird world of human beings, half animal, half children,
wholly savage and wholly heathen . . . It is an education to
see this sight, an education in the meaning and history of man. It
is to have watched the dawn of evolution. It is to have the great
moral and social problems of life, of anthropology, of ethnology
and even of theology, brought home to the imagination in the most
new and startling light.”

BUSHMAN.

Two of the most remarkable characteristics of the South African

Bushman, that “ungliickseliges Kind des Augenblicks,”

apparently
the most degraded type of humanity existing, are (1) his pictorial
talent and (2) his acquaintance with the “starry heavens above us.”
The Homeric Greek has not done more towards distinguishing the
Stars of the northern hemisphere than have the half-starved outcasts
of the Kalahari Desert or the cave-dwellers of the Drakensberg in

respect of those spangling our southern skies.

1888. | Lore of the South African Natives. 305

Miss Clerke has shown in an interesting paper contributed to
_ Nature, how Hesperus and Phosphorus, Orion and Arktos, the
Pleiads and Hyads nearly complete the list of stars distinguished
by name in the Homeric poems from the rest of the “stellar
~ multitude.” The Bushman can shew us a longer list than this.

Thus, we learn from Dr. Bleek, that the Pointers of the Southern
Cross are called the Male Lions; a, 6, y, Crucis are the Lionesses.
Aldebaran is the Male Hartebeest, a Orionis the Female Hartebeest ;
the Male Eland is Procyon. his wives are Castor and Pollux, the
Magellanic clouds are Steinboks, the Sword and the Stars in the
Belt of Orion are Tortoises, &c., &e.

Both Greek and Bushman dated their seasons by the annual rising of
the Stars; but, while the Greek pictured groups in the sky with which
he connected legends of god and heroes the Bushman traced no constel-
lations. He named the single Stars which he saw at certain periods
from the animals or other objects which at such time come into season
or became more abundant. Thus Canopus or the “Ant egg” star by

its appearance shows that this article of food might now be sought for.

The Bushmen classify the Stars into night stars and dawn stars.
_ Jupiter is known as the “‘ Dawn’s Heart,” and Leonis is her child.

The following legends profess to describe the origin of some of
the heavenly bodies :

The Milky Way was formed by a girl of the ancient race throwing

ashes into the sky.

The Sun was a man formerly living on the earth from whose arm-
pits light proceeded. It, however, only illuminated a small space
-round his house; and while he was asleep some children of the
‘ancient Bushmen were sent to throw him into the sky “since when he

shines over the whole earth.”

The Moon was caused by the Mantis or chief Bushman deity
throwing his shoe into the sky, ordering it to become the Moon and
-disperse a darkness which was caused by the bursting of the eland’s
gall bladder. The Moon is red because the shoe of the Mantis was
covered with the red dust of Bushmanland.

But according to another legend our satellite was a man who had
incurred the wrath of the Sun. The Sun attacked him with his
' knife, ¢.e., his rays, until the Moon was by degrees cut away, all but a
little piece, which the Moon implored him to spare for his children.
He then began to increase again until he reached his original size,
»when the process was repeated.

306 W, Hammond Tooke.—The Star [ Oct. 31,

KHOI-KHOI.

From the evidence that remains to us of Hottentot life, we gather —
that the Hessequa, Cachoqua or Namaqua resembled their pygmy
neighbours and foes in taking a lively interest in matters astronomical. -
Nay more, they regarded some of the heavenly bodies with a veneration
approaching worship.

Thus Dapper tells us of the tribes within the vicinity of the Dutch
Settlement uhat they had some superstition regarding the New Moon,
at the appearance of which they crowded together making merry the
whole night dancing and singing. Nieuhof says that they specially
honoured the Moon and probably did not hold the Sun in less esteem..
Leguat believed that they paid the Moon some kind of worship.
Kolb states that both at New and Full Moon they continued dancing
and singing throughout the night ; and Captain Cowley calls them
“‘ worshippers of Dame Luna.”

With regard to the tribes further north we learn from the commander
of an expedition sent into Great Namaqualand in 1761 by Governor
Tulbagh that the Namaqua religion then consisted in worshipping
and praising the New Moon.

The Nama term for “moon” is Khab, in Kora Kham “ the returner.”
The present antiquated and obliterated nature of this name (so Dr.
Theophilus Hahn concludes) points to its early application to our’
satellite, nefore the separation of the Hottentot or Khoi-Khoi clans.

Kolb speaks of it as being the “ Sichtbar Gott” whereas Ticquoa
was the “ wnsichtbar Gott.” Nama legends appear to connect the?
moon Ahab with another being Heitsi-erbib. And according to Dr.
Hahn Tiequoa or Tsui ||Goab, a word now always applied to the
Supreme Being, originally signified Red morning or Dawn, and is:
also synonymous with Hettsi-Libib, “the Dawn Tree.” Therefore,
says Dr. Hahn, it can no longer be doubtful that “the Moon is
identical with T'suz ||Goab as the ‘ Lord of Light and Life.’ ”

It at all events seems made out that the Hottentot conceptions of
the Supreme Being can be identified with the Light or Sky in its
different manifestations of the oft-recurring moonlight or victorious
dawn.

To turn to the Stars : a and 6 Centauri are called mura “the two:
eyes,” » 1 and 2 in the Scorpion are the ‘eyes of the lion.” One
of the names for Venus is “ the man with the fingers cut off.”

The Pleiads are called Khunuseti, which means offshoots or the
stars of the offshoots, namely the “ Stars of the budding season or-

1888. | Lore of the South African Natives. 307

spring,” another meaning given to them is ‘those who spring or
shoot off from one stem, a cluster.’ Both these meanings will be
found in various Bantu dialects as will be seen below.

The Khunuseti were daughters of Tsui ||Goab, the Dawn or Sky
God. It is related of them that they once said to their husband,.
‘¢Go and shoot those three Zebras for us, but if you fail to shoot, do not
return !”’ The husband went with one arrow, and shot with his bow.
He did not hit and sat because his arrow had missed the Zebras. On
the other side sat the Lion, and watched the Zebras and prevented the
man from picking up his arrow, and because his wives had cursed him
he could not return, and then he sat in the cold night shivering and
suffering from thirst and hunger.

And the Khunuseti said to the other men: “ Ye men, do you think
that you can compare yourselves to us and to our equals? ‘There
now! We defy our husband to come home because he has not
killed game.”

This legend has been pictured in the Sky by the Namaqua. The
husband of the Khunuseti or Pleiads is Aldebaran ; his bow is 7, 7? x°®
_Orionis ; his arrow three other stars in the same constellation, pro--
bably the sword ; his sandals are « and 6 of the Hyades, his kaross
is s and y Hyadum ; the Zebras are 67 and ¢ Orionis, or the three
Stars in the Belt and the Lion is a Orionis (Betelgueuse) or in another
version Sirius,

This fact would seem to show that the Hottentot differs from the
Bushman in his method of naming the Stars ; not the period of their
appearance and its connection with the seasons seem to have suggested
the names given to the stars above mentioned, but their relative
position towards each other by which they illustrate the legend.

This tradition, we may remark in passing, appears to show that in
early times the Hottentot women had enlightened views as to the
position of their sex.

BANTU.
+ Far different to the conceptions entertained by the yellow races
of South Africa of the heavenly bodies are the notions held respecting
them by the dark skinned Bantu.

The Kaffr knows and names Sun, Moon and Star, but he has no-
legends as to their creation. ‘“ These things,” to adopt Tiyo Soga’s
words, “ seem to have bafiled his imagination.” With few exceptions,
such as the Morning and Evening Star and the Pleiads, he has no
distinctive epithet for the more conspicuous stars. He never lifts

308 W. Hammond Tooke.—The Star - Ogi rs AS

his eyes to trace the patterns on “this majestical roof, fretted with
golden fire,” nor to note the rising or setting of planet or asteroid,
except as it may serve to mark the advent of the planting season, &c.

The ama Zulu and ama Xosa call the Sun JLlanga, but they seem
to regard it with no veneration and look on it neither as an ancestor
nor as a deity.

The Xosas have indeed a tradition that the creator or first ancestor,

Uhlanga, came out of a cave situated eastward “ frona whence the
.Sun issues every morning,” and this legend together with the verbal
similarity of Uhlanga to Ilanga might lead to the conjecture that
there is a common origin on the two words. And doubtless both
words bear within them the original conception of rising “ originating
from.” Uhlanga is however more closely connected with Umhlanga,
a reed, and the most common form of the myth is that Uhlanga
the first man sprang from a reed or bed of reeds. Thus it would
rather seem to indicate that the Kaffir at some early period migrated
from some marshy locality like the shores of Lake Bangweolo or the
ambatchchoked head waters of the Nile than that he ever considered
himself a Child of the Sun.

The use of the word Jlanga for Sun. seems confined to the Zulu
and Xosa tribes. The ama Mbalu or ama Langa have disused it
on account of a noted chief of their clan bearing the name and they
have substituted csota instead.

The word most universally used among the Bantu is some form
of Zuwa. Thus:

Tribe. Locality.
Ama Tonga ... Sofala ass ee Auer
Ba Nyai -.. Near Lette .. .. - Zuwa
Ma Ravi ... South of Lake Nyassa ... Dsua
Wa Sambara eae ee oe At
Wa Swaheli ... Zanzibar and Mombasa ... Jua
Wa Taveita a Zuwa
Kilimanjaro .. |
Wa Chaga Kruwa
Wa Ganda... LL. Victoria Nyanza .. Nguba
Eshi Kongo ... Sao Salvador ... .. Ntuva
Ora Herero ... Damaraland ... ... EHyuva.

‘Only among the Wa Chaga does this word connote the meaning of
God or deity as well as Sun, and this may perhaps be explained by
their proximity to the Masai or other Sudan tribes amongst which

heaven worship exists.

1888. ] Lore of the South African Natives. 309

As with tlanga (Sun) so it may be said of wyanga, the Kafir and
Zulu word for Moon, that it is rarely found in any other Bantu
language.*

Inyanga appeared to Dr. Bleek to be of Hottentot origin, and if so

‘this would show perhaps that the veneration paid by the Khoi-Khoi
‘to the Moon had had the effect on the neighbouring Kafir of inducing
him to adopt the Hottentot word. No sign of Moon worship, how-
ever, has been observed in the Kaffir, who selects a full moon for his
festivities for the same reason that we choose it for a moonlight walk
round the Kloof.

Two words are most commonly applied by the Bantu to the Moon

of which it may be said, speaking roughly, that one is in use on the
West and one on the East Coast.

The Zulu for moonlight is wnyezi, probably from an Archaic form

inkwezt (see Bleek), and we find this word applied to the Moon
.among the following tribes on the East Coast :

Wa Swaheli

Wa Nyamwezit

Ma Kwa Bat Bo Mwezi

Tette and Sena Tribes

Wa Ganda 3

Wrarjiai on. ae nee -.. Ukwezi

Wa Chaga Mwere

Wa Sambala Muezi

Wa Pokomo Muezi

-Nyassa Tribes Mwezi.
-And on the South-west :

‘Ora Herero MES sh Ones

‘Ora Ambo we

Ba Rotse ah ats ..- Moezi

Angola ... Nhs ee ... Mbeshé

Lubalo, Kisama, &c. aS --. Mbeshi.
- But among the greater number of West Coast tribes it is replaced
‘by another word as follows : :

Keubuery =: ti aoe

Diwala Ni a) peor

* T have only come across it in thetwo following Lake Tribes: Watuta, inyanga;
“Ma Nyuema, mwango.

+ Wa Nyamwezi, people of Moon land or of the Moon badge. They wear an ivory
-¢rescent moon attached to the neck.

310 W, Hammond Tooke.—The Star [ Oct. 31,-

Ngoten .-. See $e | Ween
Melon Bop mi ae
Dikele ... xa ae ... Ngondie
Babenda... ;

Ngond
Basunda... Sols bas nee
Eshi Kongo one re .-. Ngondi.

The forms mwez', unyezi, &c., are according to Dodhne connected.
with a root 2z7, meaning shining particles.

The various words in use in Kaffir for Star seem to bear the same
origin.

Thus star in Xosa is inkwenkwezi; in Zulu it is inkwezi ; while
the Xosa for morning star is *kwezi, all apparently connected with:
the Zulu and Xosa thwezikwezt, a glittering substance.

Again we have the Zulu and Xosa in-Kanyezi, a fire-fly or star»
which seems compounded of 2z¢ above-mentioned and nku-kanya, to
‘“‘ shine or emit light.”

A similar word, similarly derived, is the Zulu wewazibe, evening
star, which may be compared with whu-Cwazicwazi, brightness.

Another form of ucwazibe seems to be the Zulu icazibe, evening
star, represented in Xosa by tcanziwe.* Here zzbe or ziwe seems to:
be akin to wmsebe, a ray of light or spreading ray; compare wku-ziba,.
to separate.

Another word of different origin applied by the ama Zulu to the
evening star is zst-celankobe, from cela, meaning beggar, and inkobe,
corn. But why this star should be ealled “a beggar for corn” is
not apparent.

The root iz: glitter is seen in nyenyezi of the Tette and Sena
tribes, enyeleti at Lourenco Marques, nyuladi at Inhambane, and
mennert at Quillimane, all with the meaning of star.

In Setshuana stars are called linalert, diminutive linaletsane.

Among the ma-Koa they are called ztotwa, among the wa Swahili,
nyota.

In otyi-Herero the word for star is omyose, and seems to be
connected with nyosa, “to burn.” It is probably the same word
as myota of the Swahili just mentioned. A fixed star is o’nyose
ondikame ; zikama meaning “to be fixed”; and a planet is onyose
ondiange, the latter word from rianga, “to rove about.” The
Morning Star is called o’hingoutuku, or ‘chaser of night,” or

* Used to signify Orion by the translators of the Kaffir bible.

1888. | Lore of the South African Natives. 311

ohanumaihi, “ little drinker of sweet milk,” on account of its appear-
ance at milking time.

In Kongo a star is called ntetembwa, a term possibly connected,
asin Zulu and Xosa, with a word meaning ‘to sparkle or glitter, viz.:
tentena ; and a planet is called nkazi a ngonde, the wife of the
moon. In Bunda (Angola) a planet is chi-tetembuka.

The eshi-Kongo generally call a constellation ebundu dia ntetembwa,
or “ gathering of stars.” They have a curious name for the three
Stars in the Belt of Orion, namely mbwe yo nshiyi yo nkongwambwa,
or “ the.dog, the palm rat and the chief huntsman.”

In Kafir, Orion’s belt is simply amaroza, “ a line of stars,” primarily
-“a row of beads.”

It will be noticed that on the West Coast among the ova-Herero,
the eshi-Kongo and the Angolese a distinction is made between fixed
stars and planets.

Although generally viewing the heavens with indifference, many
Bantu tribes make an exception in favour of the beautiful star cluster
around which so many northern legends have gathered,

Miss Clerke tells us that in Arabic the Pleiads are called Eth
Thuraiya, from therwa, copious, abundant, because many are gathered
in a small space ; and that the idea of family or groups is also con-
tained in the Biblical Kimah. “ Analogy,” she says, “then almost
irresistibly points to the interpretation of the Greek Pleiads by
pleiénis, many, or pleios, full, giving to the term in either case the

obvious signification of cluster.”

We have seen that “ cluster ” is one of the meanings attributed to
the Nama Khunuseti ; among the Bantu we find this meaning unmis-
takably evident in the Herero oty’ose. This word is a form of
o’nyosé, star, plural ova nyose, and means strictly no more than
“starry,” “appertaining to stars,” “the place of stars.” Hence its
application among the ova-Herero to the Pleiad Star cluster.

In Kongo the word is udundalunda, a swarm, applied also to a
swarm of bees. ‘This closely resembles the Australian word worrul,
_a bee’s nest applied to the same asterism, and reminds us of the poet’s
“ fire flies tangled in a silver braid.”

The eshi-Kongo have, however, another word for the Pleiads za
lunda emvula, which seems to mean the “storehouse or gathering
place of rain.” (Cf Inhambane “rainy season” — nannge-nvula.)
This would appear to connect the Pleiads in the Kongo mind with the
advent of the rainy season just as the “ pluvise Hyades ”’ were so con-

312 W. Hammond Tooke.—The Star Lore, sc.

nected in classic lore ; and it may be here mentioned that while rain:
is prevalent all tle year around San Salvador, the heavy rains com--
mence about the middle of October.

However this may be, we have evidence that the Eshi-Kongo
regarded the movements of the Pleiads as betokening the succession
of the seasons ; and this gives weight to that view which would
associate the term Ahunuseti, among the Namaqua, with the arrival of
spring.

Stronger proof on this point may, however, be obtained from con-
sulting the vocabularies of the Bantu languages of the South and.
East Branches.

In Xosa and Zulu the word for the Pleiads is zstlimela, a term in
Zulu bearing the additional signification of “the breaking-up time,’”
i.e., “‘the ploughing time,” and the beginning of spring. Closely
connected with this word is the Zulu and Xosa wku-limela “to hoe,.
plough, or break up the land.”

The Kafirs would seem therefore, at one time, to have marked the.
first appearance of the Pleiads as the signal for commencing ploughing:
operations and as the harbinger of spring.

It is not probable that they applied the term zsilimela to the Pleiads
recently, for their first spring rains and therefore their ploughing
season usually commences on the frontier about the beginning of
October, while Dr. Gill and Mr. Finlay have very kindly told me
that at 32° S. Lat. the Pleiads would be seen rising just after sunset.
about November the 1éth.

Probably therefore the name was first given some centuries ago,,
when our frontier tribes were in more northern latitudes, before they
drove the Hottentots from the banks of the Bashee and Kei.

Perhaps also this word was formed before the South-east Bantu
split up into the tribes as we now know them. For the Betshuana
use almost exactly the same term for Pleiads, selemela and possibly
their word for summer, selemo, is connected therewith. At Sena,
Mozambique, and among the Makoa, pa-ku-lima, ilimue, ulima all
have the sense of ploughing or cultivation, but the writer is not aware
whether any form of this word is applied by these tribes to the Pleiads..

Among the Wa Swaheli this is the case; the Pleiads being in
Ki Swaheli Kilimia ; Kilimo meaning cultivation or planted crops.
and Kulimo, to hoe or cultivate.

A SHORT ACCOUNT OF THE ATTACKS OF THE
TEREDO NAVALIS, AND CHELURA TEREBRANS
UPON GREENHEART (WECTANDRA RODIGI) AND
SNEEZEWOOD (PTEROXYVLON UTILE) TIMBERS.

By R. H. HammersLeEy-HEEnNAN, MEm. Inst. C.E.

[READ 28TH NOVEMBER, 1888. ]

THERE is perhaps no experience more remarkable in the abstract,
or interesting in its application, than that the greatest enemies of all
life—both animal and vegetable—are to be found, in many cases, as
organisms, infinitely small, lurking in and feeding on vital tissues,
which they soon destroy. A proper understanding of the conditions
under which such organisms exist and flourish, is of the vastest
importance to applied science in almost every one of its many branches.
In surgery the advance made in this direction appears almost in-
credible.

| By the aid of antiseptics the surgeon now fearlessly enters
portions of the human body, that a few years ago he would not have
dared to touch.

Cultivators of plants now know they have enemies, which although
indiscernible to the naked eye, are, when examined under the
microscope, found to be armed with instruments of destruction, which
they use with merciless rapidity if left undisturbed.

The engineer and naval architect have also long known of one or
two of these small enemies. They belong to a class low down in the
scale of life, but for all that, they work fearful destruction wherever
they finda home. I refer to the Teredo Navalis, the Chéelura Terebrans
and the Limnoria Terebrans.

The Teredo, or the sea-worm as it is commonly called, is found in
wood (under sea-water) which it perforates, nearly always in the
direction of the grain of the timber, and lines the tunnel, or cavity, in
which it lives with a calcareous wall. ‘These tunnels, and the lined
walls, can be easily traced and examined on the specimen pieces of wood
I send to illustrate this paper, and the size of the worm itself can be
accurately estimated.

314 R. H. Hammersley-Heenan, C.E.—A Short [Nov. 28,

The Chélura, and Lmnoria, are much smaller than the Teredo,
and perhaps, for that reason are not so much dreaded, but nevertheless
they are most destructive, and whatever they may lose in size they
make up in numbers. Ido not think I have seen the latter in this
country. The former however is only too common, as I shall show
further on. The specimens marked “B” are a portion of a waling
destroyed by the Chélura.

It is far beyond the range of my attainments to give anything
approaching a scientific description of these mollusca, as my know-
ledge of natural history is painfully limited, and even if it were not
so, no useful end would be served, for it would be difficult to deal more
fully with the subject than M. de Quatrefages has done. I have
however to make a statement which, if not scientific, is none the less
indisputably and painfully true, and it is this, “ the Zeredo and Chélura
work complete destruction in timber that is considered proof against
them,” as I shall now endeavour to show. .

The Teredo navalis—as its name implies—has been the dread of
ship-builders in times past. And in Holland, and all over Northern
Europe the source of endless trouble, oak, pine, elm, and all other
kinds of timber then used in Europe succumbed to the ravages of this
pest and it was not until the year 1840, when greenheart was first
proved to be able to resist the worm in England, that timber could be
used with safety in any permanent marine works, unless it was first
protected with copper sheeting or scupper nails.

The experiments with greenheart, made some fifty or sixty years
ago at Liverpool, having given satisfactory results, this timber at
once came largely into general use for marine works, and has since
been adopted by engineers in all parts of the world, and although
in some localities it has been attacked, still the damage was so slight
as to cause but little alarm, and greenheart continued to be considered
_ Teredo-resisting timber.

The sneezewood (Péeroxylon utile) of this country is another
timber that has long enjoyed a reputation of never having been
known to yield to the attack of the worm. I shall however have
to show in the course of this paper, that both timbers have, within
my experience, entirely failed to uphold the favourable reputation
they have so long held.

About fourteen years ago the railway from Port Elizabeth to
Uitenhage was constructed by a private company, who decided
for various reasons to use timber extensively in the construction of

1888.] Account of the Attacks of the Teredo Navalis, &c. 315

its works, And the Engineer-in-charge who had had considerable
Colonial experience, decided to utilize sneezewood for the pile work
of all the bridges spanning the numerous small tidal streams that
flow into the Zwartkops river ; this timber was of the soundest and
best quality procurable, and was evidently selected with much care ard
obtained at no small cost. It was the longest of its kind that I have
ever seen, averaging about 20 feet long and about 12 inches square.

Some three years ago, Mr. J. S. McEwen, who was then the
District Engineer at Uitenhage, noticed that the piles of a bridge,
not far from Zwartkops Station were diminished in section, close to
the low water mark. At first he thought it was merely the sap-wood
that had decayed, but, on minute examination, discovered that the
Teredo had attacked the piles, and so reduced their dimensions,
that he decided to recommend that they be removed, and iron
substituted. This was done, and when the piles were taken out,
and carefully examined, it was found that they had in every case
- been more or less deeply burrowed into for about nine inches above,
and nine inches below, the low water mark. I have told these facts
to several “old Colonists” of experieace in such matters, and in
every case have been met by the remark, “it could not have been
sneezewood, the worm has never yet been known to touch it.” And
I fully believe I would have failed to convince them to the contrary
had I not been able to produce proof, which there is no possibility
of escaping from, in the shape of the timber itself, showing the
Teredo snugly incased in tunnels of its own making.

I do not think the members of the South African Philosophical’
Society will doubt the honesty of my statements ; but as it is reason-.
able to suppose that they, as a body engaged in original investigation,,
may assume that I may have been mistaken; and as it is all-.
important, that no assertion—and more especially one which is.
opposed to popular belief—should be received until subjected to the.
most searching investigation, J send a specimen-piece of the timber I
refer to—upon which the labours of the worm can be very easily
traced—in order that those interested in the subject may examine it.
for themselves.

_ Inthe first portion -of this paper I mentioned that greenheart

(Nectandra Rodiei) has long been looked upon in England and
Northern Europe as practically a Teredo resisting timber, and that in,
consequence it has been much used for marine structures, and in most
cases with marked success. It so happens however, that it falls to

N

316 Rk. H. Hammersley-Heenan, C.E.—A Short [Nov. 28,

my lot to show that not only is greenheart attacked by the ordinary
worm in this country, but that it is also a victim to the ravages of the
Chéelura terebrans, and I believe also to the Limnoria itself.

About the year 1878 the Port Elizabeth Harbour Commissioners
had two Jetties constructed, from the designs and under the profes-
sional direction of Sir John Coode, Mem. Inst. C.E. For the most part
wrought iron was used, but it was decided that the seaward ends,
known as the V heads, should be—for special reasoas—of wood, and
after due consideration greenheart was selected as the timber most
suitable for the purpose, and with this material—excellent of its kind
—the work was carried out.

Some time ago, I had to make a detailed inspection of these Jetties,
and on examining the V heads, I noticed what at first appeared to
be signs of decay in one of the horizontal pieces, and, on cutting
into it with an‘adze, found it completely honeycombed—for about
an inch deep, with the tunnels of the Teredo,’ and, on further
examination, found that all the horizontal timbers—at low water
mark—had been in a like manner attacked. I then looked to the
vertical pieces—or piles—and discovered that although the worm
had entered many of them, still the progress it had made was small,
compared to that on the horizontal pieces.

Having completed my inspection of this portion of the structure,
and having satisfied myself that the TZeredo was in undoubted and
secure possession, where it will unquestionably remain until it has
completed its work of destruction, I proceeded to examine the
timber frame—also of greenheart—that has been placed outside
the iron portion of the Jetties to act as a fender to prevent boats
coming into direct contact with the iron. I there found not only
the Terede—evidently thoroughly enjoying itself, but also, in vast
numbers, a most destructive little creature which I believe to be-
the Chélura terebrans, which does not attack the timber in the
general and haphazard way in which the Yeredo appears to do, but
invariably commences its work at the ends of the timber, or where
one piece comes into contact with another, and in this way—although
the actual area destroyed by it is comparatively small—it becomes
more injurious to a framed structure than is its great competitor.
To more clearly explain what I wish to convey, I give a simple
sketch—in plan—showing what I actually found on the day in
question. The shading represents the portions destroyed by the
Chelura.

-1888.] Account of the Attacks of the Teredo Navalis, &c. 317

a aay [oe es
SS 2 WALING

ed

pcre

It requires but litt'e technical knowledge to see that the “ cleats”
-and ‘“walings’? were rendered entirely useless—in fact so useless
that at certain points the force of the sea was sufficient to disperse
- the piles.

Since my first inspection, the result of which I have just

endeavoured to describe, I have made numerous examinations of
-these works, and have watched with interest and dismay the
advances made by these mollusca, and am now only too fully con-
vinced that before very long the question of replacing the timber-
--work will have to be faced, and when I state that it originally
-cost—for the two Jetties—some twenty-five thousand pounds, the
seriousness of my subject may perhaps be realized.

In writing this paper I have had a two-fold object in view, firstly,
a desire to let those engaged on similar works as myself know of my
experience with timbers that have heretofore enjoyed a reputation
which they certainly do not appear to me to deserve. And, secondly,

in the hope that some of those inembers of this Society who have a
special knowledge of marine insect life, and time at their disposal,
may direct their attention to the subject with a view of discovering
some means of guarding against the onslaughts of these most destruc-
tive pests. For it appears to me that the age that can boast of the
labours of Pasteur on the silkworm, should not allow the Teredo
Chélura and Limnoria to hold the field and work destruction in the
peace and security they now enjoy.

I am aware that attempts have been made in this direction from
time to time, and with varying success, but so faras I know nothing
-has yet been discovered that can be handed to the engineer and ship-
builder, with the instructions ‘‘ Use this, and your timber is safe trom
marine life attacks,” and until that be done there is something original
for science still to accomplish.

fR. H. Hammerstey-Heenan.

N2

318 F. Guthrie, LL.B.—Sea Level in South [ Feb. 27,-

SEA LEVELS IN’?SOUTH AFRICA FROM BAROMETRIC
OBSERVATIONS.

By F. Guturisz, LL.B.

[READ 27TH FEBRUARY, 1889.]

Tue tab‘e for finding sea levelaltitudes from barometric observations -
which is this evening submitted to the Philosophical Society, though

calculated according to the ordinary formula p log = is nevertheless -
p}

empirical because the coefficient » has not been determined according ©
to theory, but has been assumed, as being 64,300, so as to give correct -
results in certain cases where these results are capable of independent -
verification.

The observations on which the table is based are those which have-
been taken at the Royal Observatory and at Kimberley. Other points-
where sufficient observations have been taken and where the results can
be checked by railway levelling must be regarded as points of verifi--
cation. Of these the principal are Aliwal North, Cradock, Graham’s-
Town and Port Elizabeth. As the levels calculated by this table and:
those ascertained by telescopic spirit-levelling agree, within a few feet,.
the result must be regarded as satisfactory.

At present however the number of such points of verification is too:
small for thoroughly testing the table, which must therefore for the:
present be regarded as having only provisional value.

The table is not intended to be used to ascertain sea level from a:
’ few barometric observations, it can only be used when a continuous
series of daily observations have been taken at a fixed hour.

When such observations have been taken for four or five years at
any place, the sea level of that place ought to be deduced from the:
table with a probable error of less than 5 feet.

If only one year’s continuous observations have been taken, the
average for that year should be corrected for the average deviation:
that year from the general average over the Colony, and the result.
should still be correct within some 10 feet or so.

“1889. | Africa from Barometric Observations. 319

Even one month’s continuous observations with a similar correction
should give results sufficiently accurate to be of considerable practical
-value. As a justification for the abandonment of the theoretical
formula in the construction of this table, it may )e observed that this
formula is based on certain hypothetical conditions which can seldom
- or never exist.'

Thus it is assumed that the difference of pressure at two levels is
_ due to the weight of the intermediate vertical column of air, whereas
it is obvious that this will only be the case when the atmosphere is in
equilibrium. If there is disturbance of equilibrium, whether of rest or
niotion, this will clearly affect the tension of the air. The error in
- this case enters principally in the correction for temperature. Tem-
peratures registered by thermometers near the earth’s surface are local
and do not represent the temperature of the bulk of the super-
incumbent air stratum. Thus for example the mean of the tempera-
tures registered by two thermometers, one, say at the Observatory
_and one on the top of Table Mountain, will not, except by mere
accident, give the mean temperature of the stratum of air between
these levels. This stratum, coming as it does over vast expanses of
- ocean, has attained a temperature which can be very little affected by
radiation from a few miles of terrestrial surface, whereas the tempera-
ture registered by thermometers within a few feet of the surface
must be greatly affected by such radiation.

When the points of observation are many miles apart, as for
- instance in the case of two thermometers, the one at Cape Town and
- the other at Kimberley, the ordinary correction for temperature at the
time of observation is utterly fallacious. Whenever such observa-
tions have to be used, better results could probably be obtained by
correcting for ‘the mean temperature of the month. Barometric
pressure, as is well known, does not in any way obey the daily
._ changes of temperature. Temperature has generally but one
maximum and one minimum in the twenty-four hours, while
barometric pressure has two maxima and two minima. On the other
hand variations of average monthly barometric pressure all seem con-
nected with variations of average temperature.

It has been stated that what is at present required for meteoro-
logical purposes is not so much the collection of additional observa-
tions as the careful digestion of those which have been already
accumulated. There are, no doubt, some good grounds for this
-observation, but the experience obtained in drawing up this table

320 F. Guthrie, LL.B.—Sea Level in South [ Feb. 27,~

rather goes to shew that while we have enough good material
from which to draw useful deductions, we have on the other hand a
superabundance of bad material from which it is impossible to deduce
any satisfactory conclusions whatever. No one who has not made
himself acquainted with the facts can realize the difficulty there is in
getting a series of trustworthy observations taken under the
same conditions at one place, extending over even four or five years.
What is still more unsatisfactory is that some of the fundamental
data of meteorology are still undetermined. Jn drawing up this
table, for example, it was necessary to ascertain as exactly as possible
the average sea level barometric pressure round the South African
qaoast. This is very imperfectly known. The estimates of sea
level pressures at different latitudes, in the best works on
meteorology, are very rough and imperfect, and as far as
South Africa is concerned it may safely be said that it is
only here in the neighbourhood of the Royal Observatory where
careful observations have been made for almost fifty years that we
have anything approaching accurate knowledge on this subject.

Mr. Stone the former Astronomer-Royal of the Cape Observatory -

calculated this out from the long series of observations taken at the

amie <
Observatory and deduced a sea level barometric pressure of 30:067.

in.
with a daily average variation of from °0214 below that at 4 p.m.-

to 0243 above at 10a.m. There seems some reason to suppose that the
average sea level pressure increases very slightly towards Port
Elizabeth, and there can be no doubt that there is a very perceptible
increase when the coast trends towards the North, as at Hast

London and Durban. The average pressure at Durban is probably
about a maximum. Beyond that latitude the known equatorial depres—

sion should begin to be felt. What we know nothing about is how

4

far the daily variations which Mr. Stone ascertained to exist here -

at Cape Town can be applied to other parts of the Colony and especially

to inland stations. It may be regarded as some slight argument

that the daily variations are substantially the same elsewhere as.

they are here, that in compiling this table observations taken at
different times of the day at different localities have been reduced
to 8 a.m. according to Stone’s table of reduction, and the result as
far as it can be tested is fairly satisfactory.

The delay which has occurred in the publication of this paper in

the Transactions of the Society has enabled the writer to make.

1889. | Africa from Barometric Observations. eal

certain corrections which may add somewhat to its substantial
accuracy. In the course of a few years, with the experience which
has been learned as to sources of error, there is a reasonable prospect
that a considerable increase of accuracy may be attained in these
results. Meanwhile what has been done shews that barometric ~
observations, continued over a sufficient space of time, are capable
of furnishing very useful results as to sea level. Probably however
the approximate accuracy of these results is due to a great extent
to the somewhat exceptional climatic conditions of the southern
extremity of the African continent. There is no doubt that owing
to physical circumstances there is quite an unusual degree of unifor-
mity of average temperature over the region to which these obser-
vations apply, and it is this approximate uniformity of average
temperature that renders the calculation of sea level from barometric
observation as satisfactory as it seems to be. [tis very doubtful
whether a similar method could be applied with equally satisfactory
results to such a continent, for example, as North America, where
approximate uniformity of average temperature could not be assumed

without leading to entirely erroneous results.

322 F, Guthrie, LL B.—Sea Level in South [ Feb. 27,

Taste for calculating Sea Level Altitudes in feet of Places in the Cape,

Colony, from average 8 a.m. barometrical readings in inches,
corrected for temperature of mercury.

|
Sea Level. | Differ.

Bay. Sea Level, Differ. Bar.

1889. | Africa from Barometric Observations. 323

Heights calculated by the foregoing Taste, from the average Baro-
metric Pressure during the eleven years from 1881 to 1891

inclusive.
. Tr
Station. eee Hehe! otf erae | Ditrée
pressure. ’ |determined.
Simon’s Town.. 30°056 | 21 ath Nes S
Cape St. Francis 30°056 21 20 + 1
East London... 30°044 — 33 30 + 3 | *-(a)
Royal Observatory | 30°040 | 37 37 Olle
Cape Agulhas ... 30°009 66 58 +11 (b)
{| Mossel Bay .... 29903) IT 105 fe GS Tes
| Port Elizabeth ... | 29:887 | 180 1ST p | 1
} Dunbrody Se 29°851 | 214 200 +14
Clanwilliam ... 29°808 | (254 DAS ie ee)
| Wynberg ne ZO Se ee 4g ZoO ee Er
1 Wellington ...| 29640 | 413 | 400 | +13
Swellendam ... 29°569 479 475 + 4
@udtshoorm - 2" | 28:928 | 1081" | 10638 +18
K. Wm’s. Town 28°630) | 1329) | 134 +15
Ceres... says 28°49] 1516 | 14938 + 23
Lovedale ae 28°281 L723) 3). ZO + 3
Graham’s Town 28°146 1856) Val ar 58 les
Prince Albert ... Zs esteit| 2YVS 2120 — §
Somerset East ... 27°597 2408 | 2400 + 8
Graaff-Reinet ... 27°486 2519 2500 +19
Stutterheim ... 23d 2661 2700 = 39
Cradock .. Me er OO! 2845 2856 —Il1 :
Queen’s Town... 26°445 3597 3548 +54
Brakfoatein ... AS MAL 3946 3947 — |
Kimberley sae 26:0381 4038 4042 — 4 @
Aliwal North ... 25°(62 4328 4330 — 2 i
Bloemfontein ... 25°583 4524 4518 + 6 i
Sutherland ae ZS hoe 4513 A776 + 42

The results indicated by * are those which have been brought to the test by railway
levelling and it will be seen that the average error is about 5 feet on either side. One
source of error which the writer has not been able to eliminate is the existence in
some cases of undetermined and uncorrected index error in the various instruments
used. This will, it is expected, cease to affect the observations made in forthcoming

years, since these index errors are now ascertained in almost ‘all the instruments, and
no doubt will in future be systematically applied.

Note a. For about half the period, the barometer at Kast London was at a 40 feet
level, for the other half at 20 feet.

Note 6. The true level of the Agulhas Barometer is in doubt, it was estimated a
few years ago at 68 feet,

BOA F.. Guthrie, LL.B.— Sea Level in South [ Feb. 27,-

Subjoined is a short TABLE of Places where Observations have been’

made for not more than four years.

No. i
Station. of a Anat ‘ aoe oteenee Differ.
years. obtained.
rae ee
| Sea Point ...| 1 30-063 16 15, je. “ab ghee
1 Port Nolloth... 2 30°026 oil 40 4 Hiei
S. A. College | 4 29-976 97 Ls — 18 | *
| Stellenbosch... | 3 29°741 318 400 — 82.
| Bishop’s Court | 1 25°856 210 250 — 40)
i Storm River .. 2, 29°322 714 ce
4 Worcester 2 29:251 792 780 ee beak
j Umtata wea lhe) 27°709 2294 2400 — 106 |
; Beaufort West 2; DCT ILS 2837 2850 —A bSciae
i Kokstad 2 25°169 4979 4284 +695

Again it must be remembered that it is only in the case of those
lines to which asterisks are subjoined that we have any approach te
exact exterior measurement.

The only unsatisfactory line in this table is that which relates to
Stellenbosch. An average barometric pressure for the three years
1889, 1890 and 1891, which were in no respect exceptional in their
character, ought to have given a fairly close approximation to the
true average, and a consequent fairly close estimate of the sea level.
An error of over 80 feet is inexplicable, and quite contrary to the
experience derived from the rest of the table. It is true that the
otherwise determined sea level of 400 feet is probably an approxima-
tion by estimate only, but since the railway level is known within a
mile or so of the village, it is difficult to believe that any such serious
error as 80 feet can have been made. ‘There is, however, obviously
an error somewhere, The index error of —‘012, which seems to have
been applied in part only, will not account for this.

In the case of Kokstad there is obviously some flagrant error some-
where. How such a detailed estimate as 4,284 has been arrived at, it
is difficult to say. In the years 1886 and 1887, observation: were taken:
at Kokstad, giving an average pressure of 25°712, and a consequent
sea level of 4,383 feet, differing by only 99 feet from the estimate
4,284. Our Kokstad observations are obviously at present unavailable
until the source of this gross discrepancy can be ascertained,

1889. ] Africa from Barometric Observations. 325°

It will be seen that a much greater apparent accuracy might have
been obtained by leaving out the observations at those places where
trustworthy independent means of ascertaining sea level do not exist,
as also by omitting some which are vitiated by obvious errors. The
real utility of the table would however have been thereby diminished,
as it is very instructive to contrast those errors which may fairly be:
ealled legitimate, as they arise from the necessary imperfections of our
methods, and those which are illegitimate as arising from downright

blundering somewhere.

326 | H. C. Wilmer.— The Relation of the Sand Dune [| July 31,

THE RELATION OF THE SAND DUNE FORMATION ON
THE SOUTH WEST COAST OF AFRICA TO THE
LOCAL WIND CURRENTS.

By H. Carrington WILMER.
[READ 31ST JULY, 1889.]

Tue prevailing winds on this coast from the mouth of the Orange
River to Walfish Bay are as follows :—

First, in the summer months, namely from November to April, from
early morning to midday North to North-west, from midday light
South-west, increasing in force till from 7 p.m. to midnight, then
dying away gradually and coming round to North before day-break.
North to North-west wind brings the fog-bank on shore and some-
times carries it far inland, South to South-east carries it out to sea.

Secondly, winter months, May to October, mornings calm with light
North-west to North, fog on land, mid-day to midnight light South-
west dying away to calm. Occasional strong northerly wind for from
three to four days in succession and once at least in each month for a
period of from two to eight days, hot and very dry East wind
frequently blowing a full gale. ‘This wind generally comes on about
2 a.m., increasing in force till 10 to 11 a.m., dying away to calm in the
-afternoon ; it carries clouds of fine dust, consisting, for the most part,
of tiny grains of quartz and flakes of mica.

From Angra Pequena to Walfish Bay the coast is lined by a belt
of sand hills, varying between five and fifteen miles in width and from 50
to 800 feet high. At the back of these hills is a desert strip from
thirty to eighty miles wide, devoid of vegetation and covered by
nodules of white quartz and pinkish white felspar. This gravel
results from the decomposition of the granite, gneiss and mica schist
which form the predominant rocks of the district. As the rocks
decompose, the softer constituents, that is to say the mica and the
smaller particles of quartz and felspar, are, owing to the want of rain
to consolidate them, carried away by the winds, leaving the larger
nodules covering the surface, which is consequently white and glariug.
These fragments present the appearance of being water-worn, but are

1889.] Formation on the South West Coast of Africa, ec. 327

really only polished by the constant attrition of tbe smaller particles
blowin against them. Radiation from this glistening surface
and its bordering sand hills is necessarily very great, and as soon
as the sun rises the air becoming heated begins to ascend.
This action increases as the day advances and the heat becomes
greater ; and during the ‘summer months, when tne air over the-
_ sea is much colder and denser than that of the interior behind
the desert, a current from the ocean is introduced to fill the vacuum
caused by the ascending air. This action, increasing as_ the-
radiation increases, and decreasing again as the _ sun _ sinks,
is the cause of the rise and fall of the South-west wind so prevalent
in summer. Again, as all the rain in these parts comes in the form
of afternoon thunderstorms from the North-east and falls from
November to May, it follows, and actual observation verifies the
theory, that these South-west winds day by day drive back the
approaching rain clouds, which may be seen banked up and dis--
charging their contents to the eastward where the power of the
South-west becomes less as the distance from its generating causes,
the desert and the sea, increases. Thus a reciprocal action is in.
force; the want of rain to check denudation, by the winds, of the-
decomposing rocks and to promote the growth of vegetation causes
the desert, the radiation from which creates the South-west current ;-
while this same South-west wind, by driving back the rain continues-
the conditions which result in its own formation ; consequently there-
is but little hope of any improvement in the condition of this waste,
which is also so saline as to render afforestation or cultivation next
to impossible ; it will, therefore, probably remain a desert as long:
as the present geological conditions remain unchanged.

When, as is the case at intervals during the winter months of
May to October, the evaporation after the rainy season generates
sufficient cold to reduce the atmospheric temperature of the country
behind the desert to a point lower than that of the sea, a reverse
action is set up and wind from the East rushes in to fiil the daily
vacuum caused by the rise of the air over the heated desert; and
when, as also happens at intervals, the night temperature of the
interior falls below the freezing point, coincidently with clear weather
near the coast, this wind increases to a powerful gale. Cold at the.
eastern fringe of the desert it becomes warmer as it passes over the
heated surface, till at the coast it is a scorching sirocco, It carries
with it enormous quantities of dust resulting from the disintegration

328 H. C. Wilmer.— The Relation of the Sand Dune [July 31,

of the desert surface as already described; and as it meets the
resistance of the colder and denser stratum of air from the sea, also
struggling towards the vacuum, its force gradually becomes exhausted, ©
-and, as it dies away, it deposits its suspended particles of sand and
mica, partly on the coast and partly in the sea. Some of that which
falls into the sea is carried along by the current, which runs strongly
to the North, until a submerged reef of rocks is met with as at
Sandwich Harbour and Angra Pequena, when a portion of the sand
is arrested, the bank thus formed eventually rising above the surface ;
and thus are formed the sand spits, always trending northwards, by
which the bays of Sandwich Harbour and Walfish Bay are protected
from Southerly and Westerly winds.

Having thus shewn the effects of the sand dunes and desert on the
local winds, we will now consider the relation of these currents to
the progressive motion of the sand dunes from North to South. Dr.
F. M. Stapff, of Weissensee near Berlin, has, in his report to the
German Uolonial Society in 1886, concluded that the sand dunes of
the South-west coast were formed under the sea and afterwards
raised above its level. This is an entirely erroneous conclusion,
resulting from cursory and superficial observation, as I will proceed
to shew. In the first place the enormous quantities of sand, brought
to the coast by the East wind and partially deposited near the shore
‘as already explained, are quite sufficient to account for the extent
of the deposit. Secondly, there is a total absence of shells or other
organic remains of marine life in the sand of the dunes. Again the
sand hills are ever advancing to the North. This is caused by the
alternate action of the East wind and the South-west, which is diagonal
to the direction of the former, and thus the sand being first pushed
to the West and then back to the North-east, gradually extends itself
to the North.

In this way the sand hills have, in the course of ages, been advanced
to the North extending the desert as they extended, until they reached
the Kinsib river. They have completely choked and obliterated the
lower courses of several minor rivers, such as the Choondap and others,
which now disappear under the eastern edge of the sand dunes. The
-Kinsib river still sends down sufficient water in years of plentiful rain
in the interior to clear its bed of the sand dunes formed in it in the
intervals and thus keeps a road from Walfish Bay, where it debouches,

open to the interior. The river ran to the sea in 1856, 1864, 1881,
_and 1885, and the long intervals between gave the sand hills time to

1889.] Formation on the South West Coast of Africa, sc. 329

cross it, and form smaller hills as far as the Swakop river. This
latter however runs into the sea every year, and scours its bed clean of
-the sands blown into it during the preceding dry season. Con-
-sequently we find no sand dunes north of this river ; and also as we
travel northwards and parallel to the coast we find the desert strip
steadily narrows until in the Kaoko veldt, about 150 miles north of
the Swakop, we reach a district with a steady annual rainfall and
grass right down to the sea beach. The struggle which has taken
place between the sand and the Kinsib river is beautifully exemplified
_. between Sandwich Harbour and Walfish Bay. There is no doubt
that this river formerly debouched at the former port and has gradually
been pushed north for thirty miles, until it empties itself at Walfish
Bay. This is clearly proved by the old silt bed, with root and stems
of reeds still undecomposed, appearing everywhere wnder and between
the sand hills, while fresh water is obtainable at a depth of a foot or
two, anywhere above high water mark, between Sandwich Harbour
and Walfish Bay and nowhere else along the coast; and the spaces
' between the sand dunes are covered with water grasses and reeds
growing in the silt and nourished by the same fresh water. And in
the spaces between the sand hills near Walfish Bay are still to be seen
the deeply impressed foot-prints of elephants and rhinoceroses, in the
sunbaked silt, thus shewing that prior to the advance of the sand,
considerable vegetation, on which those animals subsisted, must have
covered the present waste.

I think I have conclusively shewn the great effect which these sand
hills have had upon the meteorological conditions of the South-west
Coast, and it only remains to point out the lesson to be derived, viz.,
_the great importance of arresting the formation of similar deposits in
their early stage by planting them with grasses and shrubs calculated
to bind the sand and thus preventing them from extending until they
become past control.

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