[Illustration:  Construction of Magic Boxes]

heads in the box and change from one to the other.

The electric globes are inserted as shown at ll through the top of the box, one in each division.  When the rear part is illuminated, any article arranged within that part will be visible to the spectator looking into the box through the front opening, but when the front part is illuminated, and the back left dark, any article placed therein will be reflected in. the glass, which takes the same position to the observer as the one in the rear.  Thus a plain aquarium is set in the rear part and one with swimming fish placed in

[Illustration:  Four Electric Magic Boxes Complete for Use]

the front, and with the proper illumination one is changed, as it appears, into the other.  When using as a window display, place the goods in one part and the price in the other.  Many other changes can be made at the will of the operator.

Electric lamps may be controlled by various means to produce different effects.  Lamps may be connected in parallel and each turned on or off by means of a hand-operated switch or the button on the lamp socket, or if desired a hand-operated adjustable resistance may be included in the circuit of each lamp for gradually causing the object to fade away or reappear slowly.

Instead of changing the current operated by hand, this may be done automatically by connecting the lamps in parallel on the lighting circuit and each connected in series with a thermostatic switch plug provided with a heating coil which operates to automatically open and close the circuit through the respective lamp.

When there is no electric current available, matches or candles may be used and inserted through the holes H, as shown in the sketch, alternately.

** Replace Dry Putty [136]

Painting over putty that has not become dry will cause scaling or cracking around the edges of the putty.

** Photo Print Washing Tank [136]

The accompanying sketch shows a simple form of a print washing tank that tips from side to side by the weight of the water.  For prints 4 by 5 and 5 by 7-in. a tank 2 ft. long and 1 ft. wide will be about the right size.  This tank is then divided with a partition placed exactly in the center.  This partition should extend 3 or 4 in. above the top of the tank.  The partition may also extend below the tank about 1-1/2 in., or a piece of this width put on the bottom, as shown at A in the sketch.

[Illustration:  Keeps Prints Constantly Moving]

A row of holes about 1/2 in. in diameter is bored through each end of the tank, as shown at B. These holes will allow the water to spill out while the opposite side is filling.  The tank may be made from 1/2-in. material and when completed as shown, lined with oil cloth to make it watertight.  The tank is placed with the partition directly under a water tap and the flow of water will cause it to tip from time to time, keeping the prints constantly moving about in the water.