Author: UNKNOWN. AUTHOR

Publisher: Forgotten Books

Published: 2015-06-12

Total Pages: 526

ISBN-13: 9781330278833

Excerpt from Van Nostrand's Engineering Magazine, 1880, Vol. 23 They have only the property of storing a small amount of motive force developed by muscular action, and of releasing it under conditions entirely different from those attending its accumulation. Thus by turning a crank slowly with considerable effort for a short time, we store up a certain amount of work which may be made to run a light machine at high speed against a light resistance, through a comparatively long time. Unfortunately only a small part of the work is utilized, and the labor of winding up the machine is far from being compensated by the useful effect obtained. The amount of work that can be accumulated in a steel spring without passing the limit of elasticity is, of course, limited. It will vary naturally with the quality and size of the spring. Experience shows that when employing the best steel known, converted to the form of a clock spring (which is the most favorable for such a service), the amount of work stored will not exceed 40 kilogrammeters for each kilogram of metal. In practice the loss from friction and deformation of the spring is about 80 per cent. It is true that the majority of the steam engines afford no better return of the total work stored in the fuel, but these latter consume coal only, while the spring motors run at an expense of muscular force, which is the most expensive and the most precious of all sources of mechanical work. M. Fontaine declared that the springs could be profitably replaced by a weight which would restore a large proportion of the labor expended upon raising it. A weight of 100 kilograms raised three meters would afford a very economical accumulator, and one less liable to deterioration. From electric engines we can no longer hope for economical results. An electric motor is nothing more than a reversible magneto-electric machine. The latter will receive a current of electricity, and under its influence will take on a rotatory movement. But from whence comes the current? From a galvanic battery or from another magneto-electric machine? In the latter case it is only a transmission of power which is effected by electricity, and it is not a solution of the problem of domestic motors. If the power is derived from a battery, then the battery is consuming zinc and acids, of which the price per unit of work is far above that of coal or gas, or any of the so-called combustibles. It suffices to know that a magneto-electric machine, worked by a single man, develops as much electricity as a battery of six Bunsen cups, each eight inches high, and freshly charged, in order to conclude that it would be necessary to employ more than six cups to drive a machine of one-man power. Engines driven by water seem much more attractive. They require no fuel nor any special agent to operate them. But while the fear of fire is not attendant upon their use, the accidents arising from freezing have their inconveniences. But here again it is the question of economy, which is of the first importance; and as the cost of water varies much in different places, M. Fontaine bases his calculations upon the conditions which obtain in Paris. This city possesses, on the one hand, a good supply of water, and on the other, supports a multitude of industries based upon indoor labor at home. The pressure of water in Paris is equal to a head of 40 meters in the neighborhood of the Seine, and only 10 meters in the higher portions. In more than half the dwellings the water cannot be delivered in the upper stories. Assuming a pressure corresponding to a head of 20 meters and an efficiency of sixty per cent, for the motor, the quantity of water necessary to afford a work equal to six kilogrammeters per second will be 1.800 liters per hour and 18 cubic meters in 10 hours. The daily expense would be four francs. There are many cities, however, in which the pressure is high and the pric...