PROCEEDINGS 
OF THE 
Cambuidge Philosophical Society. 
January 31, 1887. 
ProF. BABINGTON, VICE-PRESIDENT, IN THE CHAIR. 
The following were elected Fellows of the Society : 
S. L. Loney, M.A., Sidney College. 
R. A. Herman, M.A., Trinity College. 
A. N. Whitehead, B.A., Trinity College. 
EK. G. Gallop, B.A., Trinity College. 
The following communications were made to the Society : 
(1) On the Motion of a Ring in an Infinte Liquid. By 
A. B. Basset, M.A. 
1. The general theory of the motion of a ring in an infinite 
liquid, when there is cyclic irrotational motion through its aperture, 
was I believe first given by Sir W. Thomson in the Philosophical 
Magazine for 1871, and his theory has been subsequently developed 
by. Professor Lamb, in his Treatise on the Motion of Fluids. I 
propose in the present communication to apply these results to the 
discussion of certain special cases of the motion of a ring. 
Let G be the centre of inertia of a plane curve S, OZ any 
fixed straight line lying in the plane of S, and let OG be perpen- 
dicular to OZ. In order not to be troubled with the products of 
velocities in the expression for the kinetic energy, I shall assume S 
to be symmetrical with respect to OG, but otherwise it may be of 
any form, provided there be no singular points capable of giving 
VOL. VI. PT. II. A 
