A Mysterious Watch
Suspended watch
A very interesting experiment may be made with the ordinary dollar watch in illustrating the law of the pendulum. A pendulum 39.1 in. long will make 60 one-way swings per minute, the number of swings varying inversely as the square root of the length. By actual count it was found that the balance wheel of the watch in question made 240 one-way swings per minute, which is just 4 times as fast as the 39-in. pendulum. Therefore, according to the foregoing law, a pendulum ¹⁄₁₆ as long, or about 2¹⁄₂ in., would swing in unison with the wheel of the watch. The question then arises as to what would happen if the watch itself were suspended so as to swing as a pendulum of the latter length. The experiment was made as illustrated, with the result that the watch keeps on swinging continuously. The swing amounts to about ³⁄₈ in., and appears so vigorous that it is almost incomprehensible that the small spring in a watch should be able to maintain so much weight in continuous motion for 24 hours.