92 Proceedings of the Royal Society 
The very rapid increase of electromotive force with diminished 
resistance at the lowest speed, seems to show that the speed is very 
considerably overrated when stated as 800 or 533, with the re- 
sistance between 1 and 2 B. A. units. I hope soon to have the 
means of accurately measuring the speed realised, and shall then 
repeat these experiments for a scientific, and not a mere practical 
purpose. 
(2.) On the Law of Extension of India-rubber at 
Different Temperatures. 
To fill the vacancies in Foreign Honorary Fellowships 
caused by the deaths of Claude Bernard, Elias Magnus 
Fries, Henri Victor Begnault, Angelo Secchi, the following 
Gentlemen were elected : — 
Frank Cornelius Bonders, Utrecht. 
Asa Gray, Cambridge, U.S. 
Jules Janssen, Paris. 
Johann Benedict Listing, Gottingen. 
The following Gentlemen were duly elected Fellows of the 
Society : — 
Thomas H. Cockburn Hood, F.G.S., Junior Carlton Club, Pall Mall. 
Thomas Gilray, M.A., 6 Carlung Place, Edinburgh. 
Alex. Bennett M‘Grigor, LL.D., 19 Woodside Terrace, Glasgow. 
James BlaikiE, M.A., 14 Yiewfortli Place, Edinburgh. 
Monday, 11th March 1879. 
Professor KELLAKD, President, in the Chair. 
The following Communications were read 
1. On Gravitational Oscillations of Kotating Water. 
By Sir William Thomson. 
(Abstract.) 
This is really Laplace’s subject in his Dynamical Theory of the 
Tides ; where it is dealt with in its utmost generality except one 
important restriction, — the motion of each particle to be infinitely 
nearly horizontal, and the velocity to be always equal for all par- 
