. An elementary book on electricity and magnetism and their applications. ard an electric flatiron with the cur-rent on. It has beenfound that the iron-ing surface of theordinary electricallyheated iron should beoperated at about 500°F., if it is to be usedfor ironing damp if the ironing sur-face is not used andits heat thereby dissi-pated, it will often getred hot in less than 15minutes. This makesit desirable to use anindicating or pilotlamp connected in multiple in a heater circuit, as shown infigure 341, so that, when the current is switched on, the lampwill be lighted. While ele
. An elementary book on electricity and magnetism and their applications. ard an electric flatiron with the cur-rent on. It has beenfound that the iron-ing surface of theordinary electricallyheated iron should beoperated at about 500°F., if it is to be usedfor ironing damp if the ironing sur-face is not used andits heat thereby dissi-pated, it will often getred hot in less than 15minutes. This makesit desirable to use anindicating or pilotlamp connected in multiple in a heater circuit, as shown infigure 341, so that, when the current is switched on, the lampwill be lighted. While electric cooking may be said to be satisfactory onaccount of its convenience, cleanliness, and adaptability, elec-tric heating for general purposes can never replace the directuse of coal or the use of steam heating, until electricity isdirectly generated from the fuel or its equivalent without theintervention of steam engines. For in these there are enor-mous losses of heat, which cannot be prevented. The natureof steam engines makes it impossible, even with the best of. 341. — Flatiron on stand and connectedwith pilot lamp. ELECTRIC HEATING 487 them, to convert into useful power more than 10 or 15 percent of the heat energy contained in the coal which is shoveledinto the boiler furnace. When the steam generated by theboiler is directly used for heating, a very much greater propor-tion of the heat in the coal is converted to a useful purpose;in fact, this proportion may be so great as to lie between 60and 80 per cent. 333. Blasting and exploding mines by electricity. Theheating effect of an electric current can also be used to ignitethe charges in blasting and mining. Thecurrent is carried by a long cable from thebattery or magneto to a special fuse (). This consists of a pair of insulatedcopper wires, the ends of which project intothe detonating cap and are connected by afine platinum wire. This wire becomes hotwhen the current flows ; and being embeddedin guncotton, w
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
