1862.] 
537 
Proceedings of the Asiatic Society. 
assisted in procuring porters, and he generously gave the expedition 
the services of all his servants, and with this aid Captain Speke was 
enabled to advance. The Sheikh would travel in company with the 
expedition as far as Uganda. 
2. From Babu Gopi Nath Sen, Abstract of Meteorological Observa¬ 
tions taken at the Surveyor General’s Office in August last. 
3. From E. Blyth, Esq., a memoir on the Rats and Mice of India. 
4. From Sir Robert H. Schomburgk, a paper containing an account 
of a visit to Xiengmai the principal city of the Laos or Shan States. 
The Secretary read the paper. It will be printed in the Journal. 
Major Walker read some selections from the last report to Govern¬ 
ment, on the operations of the Trigonometrical Survey, which was 
submitted at the last meeting and which will be" published in a 
forthcoming number of the Journal. 
He then said that he was glad to avail himself of the recent publica¬ 
tion of the fourth, and last, of Archdeacon Pratt’s papers on the effect 
of Local Attraction on the operations of the Trigonometrical Survey 
to acknowledge the obligations of the survey to Mr. Pratt, for his 
theoretical investigations of this very abstruse and difficult subject. 
There was a time when the subject seemed likely to become one 
of the numerous vexatce qucestiones of science. Before Mr. Pratt com¬ 
menced his investigations, attempts had been made to prove that the 
influence of Himalayan attraction had been overlooked by Colonel 
Everest, and that it exists to an extent which would seriously impair 
the value of the Indian arc, in determining the figure of the earth. 
But Colonel Everest had paid considerable attention to the influence 
of mountain attraction in deflecting the plumb line. He had rejected 
one of Colonel Lambton’s astronomical stations in the Madras 
Presidency, because of its proximity to mountains. During a visit to 
the Cape of Good Hope he wrote a very able paper, which attracted 
much attention in the scientific world, on the effects of the attrac¬ 
tion of certain mountains, in the vicinity of the extremities of 
LaCaillies’s arc, near Cape Town. The difference between the ellipticity 
of this arc, and of those measured in Europe and Russia, was sufficient 
to give rise to the conjecture that the figures of the Northern and 
Southern hemispheres were considerably different. But Colonel 
Everest shewed clearly that the discrepancy was probably caused by 
the proximity of mountains to the ends of the arc. He suggested its 
4 A 
