Popular Science Monthly 



455 



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. 



