Zehnder's balance

This ingenious balance, which is very beneficial for demonstration experiments, can be constructed in a few minutes using pins, razor blade, cork and knitting needle.

The knitting needle is first pushed by the cork as eccentrically as possible along a line parallel to a diameter of the end of the cork.

Half cylinders are cut away from every end of the cork to produce the balance beams as shown. The supporting pins are now pushed through the cork, and can rest on slips of glass glued to a strip of wood. The sensitivity of the balance can be varied by adjusting the following pins