1862.] Proceedings of the Asiatic Society. {537 



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 vexatas 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 



