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.
From the year 1879, when Mr. Edison announced the perfection of the incandescent electric lamp, until 1903, when for a short period tantalum lamps were used, very little improvement had been made in the carbon-filament lamp. Immediately following the introduction of the tantalum lamp came the tungsten lamp, which because of its wonderfully increased capability for producing light has extended artificial illumination to a degree almost beyond comprehension. The influence of the tungsten lamp has induced a new era of illumination that has affected the entire civilized world. The development of the high-efficiency incandescent lamp has brought about a revolution in electric lighting. Its use is universal and its application is made in every form of electric illumination.
Regardless of the immense number of tungsten lamps in use, the carbon-filament lamp is still employed in great numbers and will probably continue in use for a long time to come. In places where lamps are required for occasional use and for short intervals of time, the carbon filament still finds efficient use. In one form of manufacture the carbon filament is subjected to a metalizing process that materially increases its efficiency. This form, known commercially as the GEM lamp, fills an important place in electric lighting.
Of the rare-metal filament lamps, those using tungsten and tantalum are in general use, but the tungsten lamps give results so much superior in point of economy in current consumed that the future filament lamps will beyond doubt be of that type unless some other material is found that will give better results.
The filaments of the first tungsten lamps were very fragile and were so easily broken that their use was limited, but in a very short time methods were found for producing filaments capable of withstanding general usage and having an average life of 1000 hours of service. These lamps give an efficiency of 1.1 to 1.25 watts per candlepower of light, as will be later more fully explained. This, as compared with the carbon-filament lamps which average 3.1 to 4.5 watts per candlepower, gives a remarkable advantage to the former. The tungsten lamp has a useful life that for cost of light is practically one-third that of the carbon-filament lamp.