Adjusting A Clocks Pendulum
Back in the mists of time, before people became obsessed with digital watches, clocks had things called “hands” which pointed at “numbers” on a “face” or “dial.” With these arcane devices, primitive man (say, anyone living prior to 1970) could tell what time it was with a reasonable degree of accuracy.
Later versions of these clocks ran on electricity, but earlier versions ran through mechanical power supplied by either a spring (which had to be wound regularly), or a set of weights (which had to be raised regularly). As these springs or weights released their energy, the clock would run; the rate at which the energy was released was determined by a pendulum.
The pendulum was generally a fairly substantial weight located on the end of a stick, which swung back and forth below the clock mechanism. The slower or faster the pendulum swung, the slower or faster the clock ran. Pendulum speed was determined by the distance of the weight below the mechanism - shorten the distance (raise the weight), and the pendulum would swing faster; increase the distance (lower the weight), and the pendulum would slow down.
Making the actual adjustment was generally a hit-or-miss proposition, unless you were schooled in physics and wanted to pull out your slide rule and balance. You would adjust the pendulum to something that seemed reasonable, and then check it against some other timepiece (or dial POPCORN on your rotary phone) an hour later to see how much drift had occurred. Raise or lower the weight as appropriate to speed up or slow down the pendulum, reset the hands to the current time, and check again in another hour. A good adjuster could have the clock keeping reasonable time (no more than 2 minutes' drift per hour) after three adjustments.
An important part of the process is to level the clock. An out-of-level pendulum clock with sound “tick-TOCK” of “TICK-tock,” with unequal intervals between sounds. When leveled, the sounds (which are made by the escapement) are equal and regularly spaced.
