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It is thus demonstrated that it is technically possible to place all of the wires in a city under-ground. In any other city than Paris, the above figures would be very greatly increased by the cost of under-ground piping and chambers to contain the cables. The cost of the piping and chambers is in round numbers $50,000 per mile, and these pipes are intended to accommodate one thousand wires. The cost of piping and chambers would be nearly as great for one hundred circuits as for one thousand, as the cost of chambers and the labor of excavating and filling would be the same; so that the cost for one hundred wires may be estimated at $50,000 per mile, or $500 per mile per conductor. If, then, the present method of running wires overhead is objectionable, and the expense of running them under-ground is so great as to put the cost of telephones, electric lights, and other electrical appliances out of the reach of would-be users, how are the wires to be run? It seems to the writer that much of the inconvenience may be obviated, and without greatly increasing the expense, by adopting the following plan: From each telephone exchange, electric-lighting station, or other center of electric wires, run overhead cables out to a considerable number of points about the city, some one of which would be quite near to each subscriber.

Conversation over these lines is not so easily carried on as by means of overhead wires, and it is frequently possible to overhear other conversation. The cables, of which several kinds are in use, run out from the basement of the central office through these pipes and up the side of buildings to roofs, from which they spread out to the subscribers by means of ordinary overhead lines. It is also demonstrated that the cost, even when a large number of wires run side by side, is enormously increased. The speed of working even the ordinary instruments is limited; serious trouble appears in attempting to use fast-working machines, or automatic senders, and the use of the telephone is impossible. From each of these points to the various subscribers run short stretches of ordinary house-top wire. The cost of one wire by itself is vastly larger than where many are run together, the cost of the pipe and for laying being not much greater for fifty wires than for one, and the cost of single wire cables being greater per mile of wire than multiple wire cables, so that the expense of putting such a system as one of our telephone exchanges entirely under-ground would place the cost of the instruments entirely out of reach of the subscribers.

It may be argued that cheaper methods of laying wires may be devised; but the experience of forty years has led continually to more and more expensive systems. Such a system would be more durable, needing fewer repairs, than the present, and would not be much more expensive. I'd do all this stuff more quickly, but I don't really have the money to do it all at once. I think these facts have sufficiently demonstrated that for long lines of telegraph, stretching from city to city, here in America, pole lines, which can be cheaply built, easily repaired, and where the wires can be removed from the retarding influence of the earth and the inductive influences on each other, are decidedly superior to underground lines. The distances within this city are so short that neither induction nor retardation has to be considered in the telegraph wires. The 'duplex' system, or method of telegraphing in opposite directions at once through the same wire, has of late years been applied, in connection with the recorder, to all the long cables of that most enterprising of telegraph companies-the Eastern-so that both stations may 'speak' to each other simultaneously. The cables are thus easy of access, and any new cables may be added as required without disturbing those already in use.

In London, the telegraph wires are carried from the central office to many of the branch offices and to the railways leading out of the city under-ground. Telephone wires, electric-light wires, and a large majority of telegraph wires in European cities are, however, as in America, carried over house-tops or on poles. The paraffined cables are, however, considerably cheaper, though their durability has not yet been proved. 9 However, when you size a solar installation with a battery, you also have to calculate how much energy you need. If these wires are run on poles, they not only disfigure the streets, but seriously interfere with the operations of firemen in case of fire, as we have repeatedly seen during the last few years. For many purposes, as telephony or electric lighting, a considerable number of wires start out from a central office together, but continually bifurcate until single wires run to the houses of the subscribers. That is straightforward if all devices run on the same voltage. Some devices - such as digital TVs and LED fixtures - can have the AC/DC adapter inside, which requires you to open them and remove components.

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