A very handy device for cleaning combs can be made from a piece of spring sheet brass, 4¹⁄₂ in. long and about 3 in. wide. Notches are cut in the ends of the brass with a hacksaw, making the projections as wide as the saw cut. The brass is then bent into shape with a special clamp made for the purpose, which consists of three pieces of wood, two being cut to form a curved slot, then fastened to the third piece. The brass is sprung into the slot, and then fine wire is stretched between the ends in the notches. The wire should be very fine and two strands twisted together and run through the notches.
Concealing the House Key
The time-honored custom of concealing the house key under the door mat, or in the letter box, when the family has not enough keys to go around, is so well known that an unauthorized person seeking to enter the house would look in these places first of all.
A simple and effective hiding place for the key can be quickly and easily made with the aid of an auger and two pieces of tin. Pick out an obscure section of the porch railing, and in the edge of this bore a ³⁄₄-in. hole, about ¹⁄₄ in. deeper than the length of the key. Make a piece of tin into a cylinder, the same length as the key, so that the latter will slide easily into the hole. At one end of this cylinder solder a 1-in. disk of tin, which will make it appear as in the illustration.
If the key is placed in the cylinder and the latter pushed into the hole until it is flush with the surface, it will scarcely be noticed by anyone not in the secret, and by painting it the same color as the railing it will become still more inconspicuous.—Contributed by Frank L. Matter, Portland, Ore.
A Mysterious 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.