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Rh purposes, to take the place of coal or wood. For domestic purposes, however, in the form of gas-stoves, even at the present high cost of this form of gas, it has been already largely adopted, and with advantage and economy; while for every form of light work, where power is only required intermittently, as in printing-offices, elevators, hoists, and the like, gas-engines, using ordinary coal-gas, are, even at present prices, decidedly more economical than steam, since they may be started and stopped instantaneously, and when idle are wasting nothing. And in the case of a steam-engine the steam must be kept up all the time, though the engine may not be wanted more than an hour or two in the day.

I look forward to the time, and I believe it is not far distant, when we shall have “heating-gas” laid through the streets of our cities and towns, side by side with lighting-gas and water-mains, and when our mills, and factories, and workshops, our parlors and kitchens, will be supplied with heat from that source, and when fires of wood and coal, with their abominations of dirt and ashes, and extravagance, will be looked upon as nuisances of the “good old times” when they knew no better.

To come back again to the subject of the steam-engine, from which I have digressed further than I had intended, I may mention the circumstance that the enormous wastefulness of this species of motor has originated the thought that electrical engines might be constructed to develop power more economically. A consideration of this topic, however, would take so much of our time this evening that I must pass it by with the brief remark that the galvanic battery can not compete in economy with the steam-engine, until some cheap mode of generating electricity shall be discovered. The fuel of the battery is zinc, and, even though we can get fifty per cent. of its theoretical power by burning it in the battery, its cost is so much higher than that of coal, the fuel of the steam-engine, that the latter has the advantage, at the present time, of forty to one on its side.

The recent great advances, however, that have been made in the construction and improvement of what are known as dynamo-electric machines, by which mechanical power, no matter how generated, whether from the steam-engine, the wind, or waterfall, could be directly converted into electricity, appear to have solved the problem of the cheap generation of electricity in any quantity, and have opened a wide field of speculation as to the possible extensive introduction of magnetic engines to take the place of steam. For I need scarcely tell you that electricity can be transmitted with but very little loss over great distances, by metallic conductors properly insulated, and made to drive magnetic engines to do the work of steam, or to furnish light for cities and towns, at pleasure. I shall take occasion to revert again to this very interesting topic in the course of the evening.

This remark brings us at length directly to the theme of my