104 



On the Indian Pendulum- observations. 



[Nov. 24, 



cussed, it was proposed that observations should be taken at points nearer 

 to the equator, at Ceylon, Singapore, or Borneo ; also at Aden, a position 

 of interest, " from being in a long line of depression where a large gravita- 

 tion might be expected." But as one of the two pendulums has already 

 been swung by General Sabine at three stations on or between the equator 

 and the parallel of Punnse, Captain Basevi's southernmost station, and as a 

 pendulum has been swung by Mr. Goldingham at the equator and at the 

 Madras Observatory, which is also one of Captain Basevi's stations, I am 

 inclined to think that there is no immediate necessity for taking observa- 

 tions at Ceylon, Singapore, and Borneo, and that Captain Basevi's opera- 

 tions need not be prolonged for this purpose. On the other hand, how- 

 ever, he will be easily able to observe at Aden ; and he might also observe 

 at some point in Egypt, on the plains which are crossed by the Suez Canal, 

 with the great advantage that the stations would be complementary to 

 certain of the stations in India ; thus Aden would be compared with 

 Madras and Bangalore, and the plains of Egypt with the Himalayan 

 Mountains. 



(21.) I propose, therefore, that Captain Basevi should proceed from 

 Karachi to England, taking observations en route at Aden and in Egypt, 

 and bringing his operations to a close by a series of observations at the 

 Greenwich Observatory, if the Astronomer Royal has no objections. I 

 mention the Greenwich rather than the Kew Observatory because the true 

 time can be obtained there from the astronomical clocks, whereas at Kew 

 it can only be obtained by observation ; and if (as is probable) Captain 

 Basevi arrives in the winter, pendulum-observations taken at Kew would 

 be greatly delayed, as happened when the operations were commenced at 

 Kew. Moreover, Greenwich appears to have been employed as a refer- 

 ence station for pendulum-observations more frequently than Kew. 



J. T. WALKER, Colonel R.E., 

 Supt. Great Trigonometrical Survey of India. 



