In the fixture shown at _C_ is an igniter such as is used in places that cannot be conveniently reached. To light the jet, the circuit is completed by turning the switch at _W_. As soon as the gas is lighted the switch is again turned to break the igniter-circuit. In this device the current passes through a magnet coil in the igniter which acts to open and close the circuit with the same effect as in the others. =Acetylene Stoves.=--Stoves in which acetylene is used as a fuel are quite similar in construction to those which burn coal gas. The principle of operation is that of mixing the acetylene with air in proper proportion so as to produce complete combustion when burned. CHAPTER XIII ELECTRICITY The adaptability of electricity to household use for lighting, heating and the generation of power has brought into use a host of mechanical devices that have found a permanent place in every community where electricity may be obtained at a reasonable rate, or where it can be generated to advantage in small plants. Because of its cleanliness and convenience, electricity is used in preference to other forms of lighting, even though its cost is relatively high. Electric power for household purposes is constantly finding new applications and will continue to increase in favor because its use as compared with hand power is remarkably inexpensive. Small motors adapted to most of the ordinary household uses are made in convenient sizes and sold at prices that are conducive to their greater use. Human energy is far too precious to be expended in household drudgery where mechanical power can be used in its place and often to greater advantage. Electric heating devices compete favorably with many of the established forms of household heating appliances, the electric flat-iron being a notable example. In all applications where small amounts of heat are required for short periods of time, electricity is used at a cost that permits its use, in competition with other forms of heating. The remarkable advance that has taken place in electric transmission in the past few years tends to an enormous increase in its use. The constant increase in its use for lighting, heating and power purposes is due in a great measure to the development of efficient electric generating plants from which this energy may be obtained at the least cost. In those communities where hydro-electric generation is possible its field of application is almost without end. =Incandescent Electric Lamps.=--Anything made in the form of an illuminating device, in which the lighting element is rendered incandescent by electricity, may properly be called an incandescent lamp, whether the medium is incandescent gas as in the Moore lamp, an incandescent vapor as the Cooper Hewitt mercury-vapor lamp, or the incandescent filament of carbon or metal such as is universally used for lighting.