One of the great advantages of living in a town is the abundant supply of gas and water. These necessary substances are conveyed to us along underground pipes, and a large town has miles upon miles of such pipes, extending in all directions and forming a most complex network. Gas and water companies keep a record of these pipes, with the object of finding any pipe quickly when the necessity arises; but in spite of such records pipes are often lost, especially where the whole face of the neighbourhood has changed since the pipes were laid. The finding of a lost pipe by digging is a very troublesome process, and even when the pipe is known to be close at hand, it is quite surprising how many attempts are frequently necessary before it can be located, and its course traced. As may be imagined, this is an expensive business, and often it has been found cheaper to lay a new length of pipe than to find the old one. There is now an electrical method by which pipe locating is made comparatively simple, and unless it is very exceptionally deep down, a pipe never need be abandoned on account of difficulty in tracing it. The mechanism of an electric pipe locator is not at all complicated, consisting only of an induction coil with battery, and a telephone receiver connected to a coil of a large number of turns of thin copper wire. If a certain section of a pipe is lost, and has to be located, operations are commenced from some fitting known to be connected with it, and from some other fitting which may or may not be connected with the pipe, but which is believed to be so connected. The induction coil is set working, and its secondary terminals are connected one to each of these fittings. If the second fitting is connected with the pipe, then the whole length of the pipe between these two points is traversed by the high-frequency current. The searcher, wearing the head telephone receiver, with the coil hanging down from it so as to be close to the ground, walks to and fro over the ground beneath which the pipe must lie. When he approaches the pipe the current passing through the latter induces a similar current in the suspended coil, and this produces a sort of buzzing or humming sound in the telephone. The nearer he approaches to the pipe the louder is the humming, and it reaches its maximum when he is standing directly over the pipe. In this way the whole course of the pipe can be traced without any digging, even when the pipe is 15 or 20 feet down. The absence of any sounds in the receiver indicates that the second fitting is not on the required pipe line, and other fittings have to be tried until one on this line is found. AN ELECTRIC ICEBERG DETECTOR