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T C Lethbridge – The Power of the Pendulum

I will try to explain how it works. Take some object (I usually suggest a silver teaspoon) and put it on the floor. Hold the windlass of the pendulum above it between your thumb and forefinger and unroll it very slowly. Keep the bob swinging very slightly backwards and forwards (that is oscillating). At a certain length a hesitation comes over the oscillation and after about another half inch the pendulum movement turns into a circular swing (a gyration). This is the 'rate' for silver. In practice it is 22 inches.

Experiment also shows that other things have this same rate. Lead, calcium and sodium have it and so does the colour grey. So the rate on the pendulum is not enough to distinguish silver. I had a lot of trouble in finding this out and was frequently confused when looking for silver by finding pieces of salt-glazed pottery, which were covered with calcium carbonate. The pieces of salt-glazed pottery reacted to several minerals: calcium 22 inches, carbon 12, oxygen 27, silica 14, and so on.

After a lot of experiment, it was found that the 'rate' was qualified by a second factor. When tuned in to a given object, the pendulum made a number of gyrations and then returned to a back and forth swing. Silver reacted to a rate of 22 inches and made 22 circular swings, but the colour grey only made 7 gyrations while calcium made 30. It was clear that for our pendulum code, you could write down 22:22 for silver and 22:7 for grey. For oxidised silver both would be correct.