. Locomotive text for engineers and firemen; a complete treatise on the engine, electric head-light and standard code of train rules . ectrode and the current flows through itto the electrode. These particles of carbon have a veryhigh resistance and become intensely heated by the pass-age of the current, and as long as they deposit on thepoint of the electrode, the electrode will not fuse. As previously explained, the speed at which the arma-ture revolves determines the voltage or electromotiveforce, and this in turn determines the temperature of thearc. When the speed of the armature produces
. Locomotive text for engineers and firemen; a complete treatise on the engine, electric head-light and standard code of train rules . ectrode and the current flows through itto the electrode. These particles of carbon have a veryhigh resistance and become intensely heated by the pass-age of the current, and as long as they deposit on thepoint of the electrode, the electrode will not fuse. As previously explained, the speed at which the arma-ture revolves determines the voltage or electromotiveforce, and this in turn determines the temperature of thearc. When the speed of the armature produces a voltagehigh enough to raise the temperature beyond a certainpoint, these small particles of carbon are dissipated be-fore they reach the point of the copper electrode, and theelectrode will melt or fuse, giving off a green light. When the green light is observed, and there is noth-ing else so intensely green as a shaft of light thrownout by the headlight when the electrode is fusing, thespeed of the dynamo should be reduced by throttling,and a report of the facts made upon arrival at the ter-minal. THE ELECTRIC HEADLIGHT. 315. PLATE 138. If the wires are connected in such a manner that thecurrent can pass through the solenoid 65, and enter thecopper electrode 109, and pass through the electrode andinto the carbon, the usual course of the current will bereversed, and the copper electrode will be converted intothe positive point. The arc is always created in the car- 316 THE ELECTRIC HEADLIGHT. bon point, which the current enters first. As copper willfuse at a temperature of less than 2,000 degrees Fahren-heit, and the temperature of the arc is 7,000 degrees Fah-renheit, the copper electrode would be rapidly destroyedif the wires were not changed at the binding posts insuch a manner that the current would enter the lamp atthe top, and flow down through the carbon. It is customary with some manufacturers sending outwire to be used between the dynamo and lamp to putlead ferrules
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