Page:Popular Science Monthly Volume 88.djvu/483

 Popular Science Monthly

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��A Simple But Powerful Arc-Light

THE arc-light shown can be made from odds and ends at a very small cost and can be used for many different purposes.

A piece of wood for the base, some strips of brass, a few battery binding posts, screws, drop cord and plug, and two battery carbons in a fruit-jar, with a small piece of fiber insulation, are all the articles needed to construct the light.

The fruit-jar resistance is the novel feature. Two ordinary battery carbons are held at a fixed distance from each other by two strips of fibre, the bottoms being about J/^-inch and the tops ^-inch apart.

Rubber insulation cut from an old baby buggy tire may be used for handles at the ends of the strips holding the arc carbons. By moving these handles the arc may be raised or lowered and fed together.

After the wiring is completed, fill the jar }i full of water and connect the plug with a regular 110 volt house light socket. This will make it necessary to put heavier fuses in the fuse block.

This arc will melt any substance placed between the carbons, as it will give from Vj. to 1 inch flame.

If a housing is placed over the base.

���Diagram showing relative positions of carbons

��as shown in dotted lines, and a reflector used with a common reading glass in the sleeve, the arc will cast a hght the dis- tance of a mile.

��An Electric Heater in the Garage Makes Cranking Easy

THE problem of cranking an engine on cold mornings is one of the irk- some tasks that still confronts the owner of automobiles. Radiators filled with

���Diagram of wire connection with heater

an anti-freezing mixture will resist very low temperature without congealing, but if an engine is idle over night, all the working parts become so cold that a great deal of energy must be expended at the crankshaft before even a sputter of encouragement comes from the ex- haust muffler. This can be avoided by the use of a 500 watt electric air-heater. The circuits to feed the heaters can be wired, as shown in the diagram.

About half an hour before the owner is ready to use his car in the morning, he turns the switch, which is located in- side the house, and the heater in the garage begins to warm up the engine and the fluid in the radiator. As he leaves the house he disconnects the heater from the line ; but by this time the engine, ra- diator and carburetor are warm, and at the first turn, a liberal charge of gas is exploded in the engine cylinder and the car is ready for work.

The Wireless Idea Is More Than Seventy Years Old

NE.ARLY eighty years ago the first patents on wire telegraph sys- tems were issued, in England and America. The first suggestion that wires might be eliminated came only a few years after the beginning of line telegraphy, and although "wireless" telegraphy by conduction was prac- ticed experimentally in 1842. it was not until 1895 that radio telegraphy was first accomplished.

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