Page:Popular Science Monthly Volume 88.djvu/168

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A Sprinkling Can as a Dark Room Lamp

N example of how a com- mon utensil can be converted to a purpose other than the one for which it was originally intended is shown in the illustration. A night light or a candle is placed inside a sprin- kling can set on its side, and the semi- oval opening which receives the water is covered with a few folds of ruby tissue paper affixed with music tape or glued tags. In this simple way, a very service- able dark room lamp is obtained. Venti- lation is provided for through the noz- zle ; the bend prevents the escape of light.

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��An Adjustable Arc Lamp

OODEN arms are pivoted to the wood support by a screw and washer. The upper ends of the arms are drawn together by a rubber band passed around them. The carbons are clamped in spring clothes pins, which, being fastened to the arms with one screw only, allows them to be swung up or down. By this means the carbons may be adjusted at any angle to each other.

A spool is fastened at the lower part of the wood support with a long screw and washer. Two pieces of string are tied to opposite ends of the spool, given a few turns around it in the same di- rection, and fastened to tacks at the ends of the arms. The spool is fast- ened with just enough tension so that it will stay in place no matter which way it may be turned in adjusting the dis- tance between the carbons.

Two pieces of spring brass wire are made into coils somewhat smaller than the carbons. These are sprung on the ends of the carbons, making good con-

���Popular Science Monthly

tact with them. The wires carrying the current are connected directly with these brass wires. Pieces of sheet fiber fitted in the jaws of the clothes pin clamps af- ford additional insulation, although the wood parts, if dry, are quite sufficient insulation for low voltages.

With an no voU house-lighting cur- rent, the lamp should be run in series with suitable lamp bank or other resist- ance. If the current is alternating, a choke coil may be used in series with it.

Adjustable Printing-Frame Holder

PHOTOG- RAPHERS are often re- quired to print a negative more deeply at one end than at another ; but the ordinary

method of holding the frame in the hand is unsteady and unreliable. An adjust- able support for a printing-frame, en- abling the operator to set one end fur- ther from the light than the other, is shown in the sketch. It consists of a wooden base upon which is supported and pivoted a block fitted with two up- rights. With the aid of a ratchet and swivel indicated, the block may be moved to various positions. The two uprights are also furnished with a ratchet and screw, which grasp the printing-frame in the two trough-shaped groups pro- vided in the latter. Various sized print- ing-frames may be inserted in this holder, and with the aid of the ratchets, the distances from the light to different portions of the negative may be easily adjusted.

Alcohol Burner

AN excellent alco- hol burner can be made from an oil can with the spout cut off about an inch above the body, and a wick inserted. The flame can be raised by pick- ing with a pin or any other sharp pointed instrument.

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