The book is put under a heavy weight for several hours. Thus a neat, strong cover, which looks well in a bookcase, is secured at very little expense. The eager handling by every member of the family cannot soil or deface the cover.—Contributed by Katharine D. Morse, Syracuse, N. Y.
Cloth Cover and Paper Cover Attached (Fig. 3, Fig. 4)
An Optical Illusion
A very deceiving illusion can be contrived with a bit of wire, a rubber band and a toothpick. An ordinary straight hairpin will serve instead of the wire. The hairpin or wire is bent as shown in the illustration, and the rubber band then placed on the inverted U-shaped part. A toothpick is inserted through the rubber band and a few turns taken by slipping the toothpick back and forth so it will pass the wire.
Toothpick in Rubber Band (Fig. 1, Fig. 2)
Hold the wire straight in front of the eyes, and, using the forefinger of the right hand, turn the end of the toothpick A, Fig. 1, down until it almost reaches the opposite point A, Fig. 2, and let the finger slip off. It will appear as if the toothpick passed through the wire.—Contributed by H. H. Windsor, Jr.
Temperature Alarm
The falling temperature of a room during the night may result in a very bad cold for the occupant. This may be prevented by the use of an alarm to awaken the sleeper and warn him to close the window. An alarm can be made as follows: Take a glass tube about 4 in. long and 1/4 in. in diameter and close one end, used for the bottom, with sealing wax, in which the bare end of a No. 20 gauge magnet wire is inserted. The tube is almost filled with mercury. On the mercury a float of wax is placed in which a bare piece of the same magnet wire is inserted and bent as shown in the sketch. The tube of mercury is fastened to a base with two clips of metal. At the upper end of this base the adjustable lever A is attached. The electric connections are made as shown in the sketch.