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ELECTRIC TRANSMISSION OF ENERGY.

INTRODUCTORY.

THE transmission of energy and its transformation is the fundamental problem of mechanical engineering. No piece of mechanism yet devised is able to create energy, but all mechanism has for its object the transmission and transformation for useful purposes, of energy already existing in nature in a more or less inconvenient form. The more perfect our mechanical appliances, the better are they fitted to direct the forces of nature to do useful work; and in this sense the electric transmission of energy must be regarded simply as an improvement on purely mechanical methods already existing. But it is something more. It not only improves mechanical methods, but extends the field for their application, inasmuch as it can, in many instances, reach nearer to the sources of power than any mechanical means.

The most important natural sources of power are fuel, wind, and water. As regards the first-named, electric transmission can hardly be considered of any great importance for the purpose of reaching the source of power, for fuel, especially in its most useful form of coal, is so

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easily portable, that in most cases it is more convenient to carry the fuel to the place where the energy is required than to transform it into energy where found and transport the energy to the place of application. It has been suggested to erect large generating stations for electricity close to the pit's mouth, and work the dynamos by steam-power obtained from the small coal which is not worth being carried by rail. The current generated could then be sent along wires to neighbouring towns, and thus the energy contained even in the refuse of our coal-fields could be utilized. As yet this suggestion has not been carried into practice, except on a very limited scale, namely, in providing motive power for underground railways in coal mines.

The other two great natural forces, wind and water, especially the latter, offer a larger field for the application of electricity. Water-power is only portable in a very limited sense. The great cost of channels, and the difficulty of providing elevated reservoirs close to those places where the power would be of greatest use, compel us in most cases to establish our factories close to natural waterfalls; in other words, we cannot carry waterpower to the work, but must take the work to where the water-power is. Where that is impossible or inconvenient, the power cannot be directly utilized. It is in these cases that electric transmission of power is of greatest value, inasmuch as it enables us to get at many sources of energy which would otherwise be wasted. The amount

of energy contained in waterfalls all over the world is enormous. To cite only one or two cases. According to Herr Japing, the hourly weight of water falling in the Niagara is one hundred million tons, representing about sixteen million horse-power, and the total production of

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coal in the world would just about suffice to pump the water back again. M. Chretien, a French engineer, has in a paper read at the Paris Electrical Exhibition in 1881, given the total water-power in France as seventeen million horse-power, and has suggested, that if by electric transmission only a part of this vast amount of energy were made available for useful purposes, an enormous economy in the consumption of fuel in France would be effected, and, at the same time, the hydraulic works necessary would also have the beneficial result of preventing, or at least mitigating droughts and inundations. This suggestion has already borne fruit, although only on a small scale. Near Bienne, in Switzerland, there is a waterfall representing an energy of several thousand horse-power. A small portion of this power is utilized by a turbine, which works a generating dynamo. The current is conveyed by an overhead line, consisting of a pair of copper wires (270 mils diameter) to Bienne, a distance of about a mile, where it works two electro-motors; one in a mill where silver is rolled, and where the power required is very variable; the other in a watch factory where, on account of the delicate nature of the work, an absolutely constant speed is required. The installation has now been at work with perfect success for over two years.

Another instance of electric transmission in connection with water power is the electric railway at Portrush, in Ireland, where the energy of a waterfall is by means of a turbine and dynamo converted into electrical energy, which is conveyed to the line and along the rails into the motor of the car. There it is reconverted into mechanical energy and utilized in propelling the car. Examples of this class might be multiplied, but these two will suffice to show that a practical beginning has already been

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