This can be shown by a beautiful philosophical toy, which may easily be
constructed. Procure a glass jar and put water into it. Then mold three
or four little figures in wax, and make them hollow within, and having
each a minute opening at the heel, by which water may pass in and
out. Place them in the jar, and adjust them by the quantity of water
admitted to them, so that in specific gravity they differ a little from
each other. The mouth of the jar should now be covered with a piece of
skin or india-rubber, and then, if the hand be pressed upon the top
or mouth of the jar, the figures will be seen to rise or descend as
the pressure is gentle or heavy; rising and falling or standing still,
according to the pressure made.