Electricity in Homes and Workshops; A Practical Treatise on Electrical Apparatus (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ... with batteries for the bells. The Strength of Telephonic Apparatus Generally.--A few remarks on this head may not be amiss. Whatever the purpose for which the apparatus is required, the strongest is always the cheapest. The electric currents that transmit and reproduce speech are very weak, and will easily pass through very small wires and very small connecting pieces; but the hands that use telephonic apparatus are not always weak, and frequently by no means gentle. Further, the apparatus, whatever it may be used for, is subject to expansions and contractions with varying changes of temperature, to the peculiar action of the current itself, tending to render the ends of connecting wires and connecting pieces brittle, to the presence of dust, deposited and created by the minute sparks which pass between working parts, often to the flicking action of the end of a duster, and to many other trials, all of which need strength to withstand, if the apparatus is to be of service, and to continue of service for as long as it is wanted. The use of " Earth " as a Return for Telephone Wires.--The use of "earth" has practically ceased for telephone work. The disturbing effects of induction from other wires, which is considerably lessened by doubling the wires; the disturbing effects of the leakage currents from wire to wire through earth connections; the disturbing effect produced by the neighbourhood of electric light and power-currents, added to the frequent troubles caused by the uncertainty of the earth connection itself, have led to the use of the metallic return, with the exception, of course, of those special cases where no disturbing effects arise from the use of "earth," and where the "earth..".