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VIII. Account of recent Pendulum Operations for determining the relative Force of 
Gravity at the Kew and Greenivich Ohservatories. 
By General J. T. Walker, C.B., R.E., F.R.S., LL.D. 
{Commu7iicated at the request of the Kew Committee.) 
ReceiYed April 15—Read June 5, 1890. 
The recent pendulum observations for the purpose of determining the gravity 
connexion between the Royal Observatory at Greenwich and the Royal Society’s 
Observatory at Kew, were undertaken in order to improve and strengthen the con¬ 
nexion between the Indian series of pendulum operations and other series taken in 
other parts of the world. 
The Indian series had been carried out in the years 1865 to 1873, when two 
invariable pendulums, the property of the Royal Society, which had been designed 
by Captain Kater for the purpose of investigating the relative force of gravity in 
different latitudes, were swung at the Kew Observatory, and at various places in and 
on the way to India, in the course of the operations of the Great Trigonometrical 
Survey of India. The work was originated at the suggestion of the President of the 
Royal Society, General Sir E. Sabine ; the greater portion was performed by Captain 
J. P. Basevi, R.E., who lost his life from exposure while operating on the high table¬ 
lands of the Himalayan Mountains; the remainder was completed by Captain W. J. 
Heaviside, R.E. ; both officers acted under the personal superintendence of General 
J. T. Walker, the Superintendent of the Great Trigonometrical Survey. 
The points at which the pendulums were swung and the number of vibrations they * 
made in 24 hours were determined, were mostly stations of the Central Meridional 
Arc of the Survey which extends from Cape Comorin to the Himalayan Mountains ; 
a few stations were added on the East and West Coasts of India, and on neigh¬ 
bouring islands, and ako at Aden and Ismailia. The base station of the entire series 
of operations—that is to say, the one at which they were commenced and concluded—- 
was the Royal Society’s Observatory at Kew, near Ptichmond, Surrey. 
With a view to effecting a connexion between the operations in India and similar 
operations recently completed in Russia, and also for other reasons, two reversible 
pendulums, the property of the Russian Imperial Academy of Sciences, which had been 
employed in Russia, were sent out to India and swung at some of the Indian stations, 
pai'i passu, with the pendulums of the Royal Society. 
MDCCCXC. —A. 3 z 
30.9.90 
