Electric Lighting for Marine Engineers; Or, How to Light a Ship by the Electric Light and How to Keep the Apparatus in Order, with 134 Illustrations

Paperback / softback
This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1896. Not illustrated. Excerpt: ... chapter V. switches and cut outs. Next come switches and fuses or cut outs, as they are termed. The office of the former is to control any individual lamp or group of lamps, by allowing the current to pass or cutting it off at will The term, like a good many of those that have come to us from the early pioneers in applied electricity, the telegraph engineers, was originally borrowed from the apparatus used on railways for the purpose of diverting the course of a train from one line to another. Switches used in telegraph work are often made to change the direction of the current from one wire to another, from working one apparatus to another. As they were occasionally used for breaking the circuit also, the term has been handed on to electric light apparatus. In the latter, too, we occasionally have switches to divert the current from one lamp to another, or to connect a lamp or group of lamps to either of two or more sources of current. The simplest form of switch, that which merely makes and breaks the circuit, causing the lamp to burn or the reverse, consists of two or more metal parts, one of which is movable and the others stationary. The whole of the parts are mounted together on a base of insulating material, such as hard wood, vulcanite, slate, or porcelain. The earlier switches were all mounted on hard wood, and some of them are still doing good service; in fact, in the writer's opinion, the all-round qualities of good hard box or ebony are superior to those of either porcelain or slate. Wood, however, fell into disgrace, because that used in the early days of electric lighting often was not hard. It was sometimes soft, readily absorbed moisture, and thereby lost part of its insulating properties. Further, many of the early switches were badly constructe...