Electricity in Our Homes and Workshops (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1890 Excerpt: ...that there is an actual break. The long circuit, however, will show a deflection as long as there is no actual break; and it is therefore possible, by testing with both circuits, and comparing the deflections obtained with former tests, to form a fairly accurate judgment as to the cause of failure. It will sometimes happen in the case of pushes, as of wires, where they have been fixed upon damp walls, that the damp has found its way into the push, destroying the connection by the layer of oxide or chloride of copper formed. Sometimes the effect will be only to weaken the current by the extra resistance offered by the film of oxide; in other cases the wire may be eaten quite in two. More frequently, where a fault occurs at a push, it will be due to the wire having broken off short where it is clamped under its screw; and it will often cause considerable annoyance by sometimes touching its spring, allowing the bell to ring, and then a little later, perhaps owing to some vibration in the house, say, due to a passing heavy vehicle, the connection will be broken, and it will fail. Either of these faults, breakage or oxidation, are visible immediately the push is examined; and the latter generally gives warning, by its bell ringing weaker and weaker as the oxidation progresses. Occasionally, where push springs are not tipped with platinum, the dirt formed by the spark will cause trouble, as before explained; but this is usually where other parts of the system are weak. If the battery and bell are as powerful as they ought to be, the ringing rarely stops from that cause. A not infrequent fault with the pear pushes and silk ropes that have been described, and a somewhat troublesome one, is a break in the flexible wire inside the cord. In order that it may be very f...