An example of unstable equilibrium is shown in the accompanying sketch. All that is needed is a 2-foot rule, a hammer, a piece of string, and a table or bench. The experiment works best with a hammer having a light handle and a very heavy head.

Illustration: An Experiment in Equilibrium

Tie the ends of the string together, forming a loop, and pass this around the hammer handle and rule. Then place the apparatus on the edge of the table, where it will remain suspended as shown. --Contributed by Geo. P. Schmidt, Culebra, Porto Rico, W. I.