Page:Popular Science Monthly Volume 92.djvu/316

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GLUE that is waterproof, is very useful to have around the house for various repair jobs, as well as for new work in the amateur experimenter's shop. Waterproof glue is superior to the ordinary kind, as it resists dampness and is richer in adhesive properties. The formula is as follows: Soak ordinary glue in water until it swells up, but does not lose its shape. When it is thus softened, drain the superfluous water from it and transfer it to a glue pot. Add an equal quantity of linseed oil and boil the mixture over a slow fire until a jelly-like mass results. It is then ready for use. Such glue will join various materials in the most satisfactory manner. It holds remarkably well, dries quickly and resists moisture. It can be depended upon in every respect.

HE feature of this trick is that three jacks and a king are withdrawn from the pack which is shuffled. Then the four cards are placed in various parts of the pack and the pack is cut. When examined it will be found that the three jacks and the king have rejoined one another and are now all together in the center of the pack.

Begin by taking out the three jacks and one king, and, while looking over the pack for these cards, contrive to slip the fourth jack to the bottom of the pack. Give a false shuffle, leaving the fourth jack at the bottom of the pack. Now, proceed to place the four cards in various parts of the pack as follows: Place one of the jacks at the bottom of the pack, one at the top, and one in the center at any point. Place the king on top of the pack. By this arrangement of the cards there will be two jacks on the bottom of the pack and one king and a jack on the top. It is obvious that if the pack is cut, all four of the cards, the three jacks and the king, will be brought together in the center of the pack.

The jacks finally shown are not the ones originally selected, the one placed in the center of the pack is lost, and its place taken by the jack secretly placed at the bottom of the pack prior to the commencement of the trick. It is very seldom that this fact is noticed by the audience.

HE practical pond microscopist quickly discovers that the glittering brass and glass paraphernalia supplied by the optician are not only unnecessarily expensive but often by no means well adapted to his requirements. The several devices herein described can be made easily and will be found to serve a variety of purposes.

For low power work, where an objective that will work through an ordinary 3 by 1-in. slip is used, the slip described herewith, will be helpful. Two 3 by 1-in. glass strips are used, shown at A in Fig. 1. Inclosed between them is a rubber ring B from which a piece has been snipped with a pair of scissors. A piece of hard wood C is slipped over each end. In this, a groove is cut the requisite width to hold the glass pieces together. Put just sufficient pressure on the rubber to prevent leakage of water. Two or three such slides can be made, using rings of different thicknesses.

An exceedingly simple life chamber, but one that is useful for many purposes, is made by turning a ring of paraffin wax on the object slide; covering it with a thin glass. Two or three very small threads should be