The Coin in Equilibrium.
Here is a curious demonstration of the balancing of bodies having their center of gravity displaced by a counterpoise.
We propose to keep a coin horizontally in equilibrium on the rim of a tumbler, and it must rest on the glass only by its extreme edge, as shown by the figure which gives the complete demonstration.
Take a silver dollar and place it between the prongs of two forks covering each other, then place the edge of the coin upon the glass and draw the handles of the forks together, or distend them till the whole are balanced. The center of gravity will then be at the point of contact, and you may give a slight swing without the risk of breaking the equilibrium thus obtained.
The Submerged Coin.
In order to make the previous experiment more significant, you may present it also in the following manner: In a soup plate place a coin; beside the latter an inverted glass, then pour water into the plate just to cover the coin. You then inform the spectators that you will withdraw the coin from the plate without wetting your fingers. You will meet with a great deal of disbelief from many of your friends looking on. Leave them in doubt as to the success of your operation.
Cut a round piece off a cork, on the top of which place some pieces of paper and matches, push the whole underneath the glass, light the matches and wait. As soon as the combustion is over, you will see the water leave the plate and enter the glass, wherein it rises, leaving the piece absolutely dry at the bottom of the plate. You can then execute what you offered at first—take out the coin without wetting your fingers.