1886.] Rev. H. J. Sharpe on Motion of Compound Bodies. 29 
Monday , 20 th December 1886. 
Sir WILLIAM THOMSON, President, in the Chair. 
The following Communications were read : — 
1. Motion of Compound Bodies through Liquid. By the 
Rev. H. J. Sharpe, M.A. Communicated by the 
President. 
It is well known that the solution of the mathematical problem 
of the motion of liquid arising from the motion through it of 
solids has been effected in comparatively few instances, and in 
these, such as the sphere and the ellipsoid, the surface is defined by 
a single equation. In the following investigation, however, we 
seem naturally to come across cases where the solid might be 
described as “a compound body,” consisting as it does of parts 
defined by different equations. It is possible that the method 
employed might lead to the solution of analogous problems in 
Sound, Heat, or Electricity. 
DBAB'D' is the trace on the plane of the paper of a material 
cylindrical surface, which is supposed to move through an infinite 
mass of water in direction OA with a velocity which at the instant 
