300 



How to Make a Strong Glue That 

 Will Withstand Moisture 



A 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. 



Popular Science Monthly 



Another Card Trick— the Inseparable 

 Jacks and King 



THE 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 jacks and a king are withdrawn from 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, pro- 

 ceed 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 commence- 

 ment of the trick. It is very seldom that 

 this fact is noticed by the audience. 



Making Simple Life Slides for 

 Microscopic Work 



THE 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 re- 

 quirements. 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, 



Two strips of glass with rubber ring be- 

 tween, held together with wooden pieces 



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 to- 

 gether. 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 



A reservoir slide to hold nutritive fluid 

 that is convenient for examining algae 



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 



