Prof. Henry on the Conservation of Force. 41 
— of power. In this respect it is precisely analogous to 
man, and an equal amount in the machine, locomotive. The 
result derived from an analysis of the food in one case, and 
the weight of the fuel in the other, and these compared with 
the quantity of water raised by each to a known elevation, gives 
the relative working value of the two machines. From this 
possible from materialism ; it requires a separate t inking prin- 
_ Ciple. To illustrate this, let us suppose a locomotive engine, 
equipped with steam, water, fuel—in short, with the potential en- 
gy necessary to the exhibition of immense mechanical power; 
the whole remains in a state of dynamic ern without mo- 
i e engineer now open a 
valve which is so poised as to move with the slightest touch, and 
amost with volition, to let on the power to the. piston; the ma- 
chine now awakes, as it were, into life. It rushes forward with 
tremendous power, it stops instantly, it returns again, it may be, 
at the command of the master of the train ; in short, it exhibits 
Signs of life and intelligence. Its power is now controlled by 
mind—it has, as it were, a soul within it. The engine may be 
Serge as an a endage or a further development of the 
y of the 
additional capacious stomach for the evolution of power; and 
the wheels, the cranks and levers, the bones, the sinews, and the 
muscles, by which this power is applied. 
Washingtou, D. C., 1860. 
SCOND SERIES, Vor. XXX, No. 88.—JULY, 1860. 
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