306 Proceedings at the Meetings. 
May 19th, 1913. 
In the Cavendish Laboratory. 
Dr SHIPLEY, PRESIDENT, IN THE CHAIR. 
The following were elected Fellows of the Society : 
P. G. Bailey, M.A., Clare College. 
Franklin Kidd, B.A., St John’s College. 
Rev. M. J. Le Goc, B.A., Fitzwilliam Hall. 
G. Udny Yule, M.A, St John’s College. 
The following were elected Associates : 
F. EK. Baxandall. 
C. P. Butler. 
W. Moss. 
W. E. Rolston. 
The following Communications were made: 
1. (1) Some methods of measuring the surface tension of soap 
films. 
(2) A simple method of testing lens systems for aberration. 
By Dr G. F. C. Szarue, Peterhouse. 
2. On the Unstable Nature of the Ion in a Gas. By R. D. 
Kireman, B.A., Emmanuel College. 
3. A Dust Electrical Machine. By W. A. Dovucetas Rupes, 
M.A., St John’s College. 
j 
: ; 
4. A mechanical vacuum tube regulator. By R. WurppiIneTon, — 
M.A., St John’s College. 
5. The hydrodynamical theory of lubrication with special reference — 
to air as a lubricant. By W. J. Harrison, M.A., Clare College. 
