526 Mr . Cavendish’s Experiments , &c. 
would be equal to 2 x ,1231 x ,61 x -J cubic inches, or ,201 
spheric inches of water, placed at the distance of one inch from 
the centre of the ball. In reality, it can never be so great 
as this, as the attraction of the outside surface is rather less 
than that of the inside ; and, moreover, the distance of x from c 
can never be quite so great as ,75 of an inch, as the greatest 
motion of the arm is only ij inch. 
