60 
NATURE 
[NovEMBER 19, 1903 
storage have largely disappeared. For the rapid re- 
production of maps photozincography was, until a few 
years ago, the method invariably used. Two new 
methods have now superseded photozincography ; one 
of these, “* heliozincography,’? was worked out by the 
Ordnance Survey, and subsequently adopted by the 
Survey of India; the other, the ““Vandyke process,’’ was 
invented by Mr. Vandyke, of the Survey of India, and 
has now been adopted by the Ordnance Survey. The 
first method consists in reproduction direct on a sensi- 
tised zine plate in contact with a reversed negative. 
The Vandyke process consists in reproduction direct on 
a sensitised zinc plate in contact with the original 
drawing. Lately, at Southampton, it has been even 
found possible to reproduce maps drawn on thick draw- 
ing paper. The process has been patented by Mr. 
Vandyke, and is a cheap and very efficient means of 
reproducing cadastral maps. 
(2) Geodetic Triangulation in Burma.—The principal 
point to note is the determination of the coefficient of 
terrestrial refraction by night as well as by day, the 
coefficient being the absolute refraction divided by the 
terrestrial arc. By day (from observations to helio- 
stats between noon and 3 p.m.), the coefficient was 
0.072; by night (from observations to lamps), 0-083. 
It is possible that if the night observations had been 
taken from midnight onwards the coefficient would 
have been smaller. 
Some interesting 
Manipur series) was 
being 95 miles long. 
(3) Latitude Operations.—The average probable 
error of 14 latitudes observed with a zenith telescope 
was +0".063, or say six and a half feet. India is, of 
course, committed to the system of refined latitudes, 
and comparatively few of them. 
(4) Experiments with the Jéderin Base Apparatus.— 
A base was measured at Dehra Dun with the following 
results :— 
secondary triangulation (the 
also carried out, one of the rays 
By Jaderin apparatus... 
By Colby’s bars 
a discrepancy of 1/194,000. 
It was found that the 80 ft. wire was the most con- 
venient, and various practical suggestions are made 
oa the use of the apparatus. It was apparently in 
contemplation to measure a Jiaderin base in Burma. 
There would appear to be no doubt as to the gain in 
speed, and also no doubt that it is possible under suit- 
able conditions to do away with base-line figures by the 
use of, say, 15 mile bases. 
(5) Magnetic Survey of India.—This has been com- 
menced, and there are now five base stations, Calcutta, 
Bombay, Rangoon, Dehra Dun, and Kodaikanal. It 
was intended in 1901 to send out three field detach- 
ments to work in an area west of a line joining Dehra 
Dun and Bombay, two to work along railway lines, 
and a third in the desert. 
(6) Tidal and Levelling Operations.—Tidal observ- 
ations have been, or are being, taken at forty-one ports 
in, and adjacent to, the Indian Empire. Tables are 
given of the tidal constants at various ports deduced 
from the 1900 observations. As regards the accuracy 
of prediction, at fourteen open coast stations during 
1900 it was found that the mean error of prediction 
of the time of high or low water was thirteen minutes, 
and the average error of predicted heights was one 
twenty-fifth of the range. 
The tide-predicting machine belonging to the Indian 
Government (due, it is believed, to Lord Kelvin and 
Mr. Roberts) is in London, and the Survey of India 
sends home annually the latest values of the tidal con- 
stants to Mr. Roberts, who sets the instrument for the 
port in question, and causes it to describe graphically 
NO. 1777, VOL. 69] 
39,187-272 feet 
39,187-462 ,, 
the tide curve for any future year required. As Prof. 
Darwin has remarked in his book on ‘‘ The Tides,’’ 
it is characteristic of England that this admirable 
machine has not been made use of for any of the home 
ports. 
(7) Topographical Surveys.—The seventh report 
deals with some details of one-inch work in Burma, 
and incidentally serves to emphasise the necessity 
of keeping cadastral and topographical work distinct. 
The topographical surveys are fully described in the- 
annual report, the most interesting being the survey 
on a scale of half inch to one mile of 17,000 square 
miles carried out in China during the expedition. 
When shall we have an Imperial Survey capable o° 
doing for the Crown colonies, protectorates and 
occupied territories what the Survey of India does for 
India? C. ERE 
ISAAC COOKE THOMPSON. 
IVERPOOL has lost a well-known naturalist in 
the death of Mr. I. C. Thompson, who was 
hon. treasurer of the Liverpool Marine Biology Com- 
mittee from its foundation nearly twenty years ago. 
He had a wide knowledge of the Crustacea, and 
especially of Copepoda, the group upon which most of 
his original work was done, but he was also a keen 
field-naturalist, interested in the lives and habits of his 
animals, and preferring to catch the specimens himself 
and to examine them in the first place alive. He was 
always a prominent member of the party during the 
dredging expeditions in the Irish Sea and at the Port 
Erin Biological Station. Little more than a month 
before his death he was one of the leaders in the British 
Association dredging excursion which followed the 
Southport meeting. 
Thompson’s early papers on the Copepoda dealt with 
the forms found in Liverpool Bay and other parts of 
the Irish Sea, but he collected wherever he went, and, 
as the result of vacation travels, published papers 
on the Mediterranean and Norwegian species and on 
collections from Madeira, the Canaries, the west 
coast of Ireland, the Faerée Channel, and a traverse 
through the North Atlantic to Quebec. He also 
described Copepoda from the Bay of Bengal, the 
Antarctic, the Red Sea and east coast of Africa, and 
recently from the Oceana Expedition in the North 
Atlantic. In these papers he described many new 
forms, aided in the elucidation of not a few obscure 
points, and greatly extended our knowledge of the 
geographical distribution of the group. Thompson’s 
last piece of scientific work was a large report, under- 
taken jointly with Mr. Andrew Scott, upon the Cope- 
poda of the Ceylon pearl banks, recording more than 
280 species, of which 76 are described as new to 
science. This extensive work was completed some 
weeks ago, and Thompson passed the last of his sheets 
for press shortly before he was struck down; it has 
been referred to by one who saw the proofs as the 
pioneer work on tropical Harpacticide and Licho- 
molgide. Thompson’s papers have been published for 
the most part in the Transactions of the Liverpool 
Biological Society, the Journal of the Linnean Society, 
the Annals and Magazine of Natural History, and the 
reports of the British Association. He was in corre- 
spondence with Claus, Richard, Giesbrecht, and other 
Continental workers, and’ frequently supplied them 
with British specimens required for comparison or de- 
scription in their monographs. 
There were few of the local organisations in Liver- 
pool for the advancement of science and the appli- 
cations of scientific teaching in which Mr. Isaac 
Thompson did not play a prominent part, and his posi- 
