The engine will then be in proper tram on this side, or, in other words, the distance from the centre to centre of the crank pins will be the same as that from centre to centre of the axles.
On the other side of the engine the process is the same, the engine being moved until the crank pins are on the line of centres c c and the wedges set up according to the lines.
Chapter XXXIX.—THE MECHANICAL POWERS. LEVERS, PULLEYS, GEAR WHEELS, ETC.
Power is distinguishable from force or pressure in that the term power means force or pressure in motion, and since this motion cannot occur without the expenditure of the force or pressure, power may, with propriety, be termed the expenditure of force or pressure.
If we suppose a piston to stand in a vertical cylinder sustaining a weight upon its surface and compressing the air within the cylinder, so long as there is no motion no work is done, as the term “work” is understood in a mechanical sense, and the weight merely produces a pressure. If, however, the weight be removed, the compressed air will force the piston upward, performing a certain quantity of work which may best be measured by the amount of power exercised or expended.
The mechanical value of a given amount of power cannot be either increased, diminished or destroyed by means of any mechanical device or appliance whatsoever through which it may be transmitted.
It may be concentrated, as it were, by decreasing the amount of its motion. It may be distended, as it were, by increasing the distance through which it moves, or it may be expended in giving or producing motion, but in either case the amount of duty or work done is the exact equivalent of the amount of power applied.
A gain or increase in speed is not, therefore, a loss of power, but merely a variation in the mode of using or utilizing such power.