Balancers Redux

Abstract

In 1981 I published a note on “Balancers” as part of a series of illustrations drawn from 19th-century physics texts. Some months later a wonderful present arrived from a physics teacher in Japan, showing the range of our journal. This was the Horse and Rider Balancer in Fig. 1 that was just like the woodcut in my note. The little device, only 23 cm high, sits on a shelf in my museum of early physics teaching apparatus, and many visitors are drawn to it. This is a standard piece of early physics demonstration apparatus. The addition to the lead ball attached to the horse brings the center of mass below the point of suspension. Any movement from this equilibrium point raises the gravitational potential energy of the system and it oscillates until it gets into equilibrium once more.