Moving Force. 169 
steam be not wholly applied in producing the 
intended effect, the loss must be owing to 
_ practical imperfections in the construction of 
the apparatus. Such imperfections must exist, 
more or less, in every apparatus, and they will, 
‘no doubt, be greatest in extreme cases. But 
although the whole heat, or the whole force, 
can, in practice, never be completely transferred 
from one given object to another, yet there 
can be no doubt of the real existence of both 
the heat and the force in their full quantities ; 
and we can form no idea of the portion of time 
being limited in which the one must be evolved 
or the other transferred. 
A water-wheel may be made to move with a 
ei so great, that almost the whole pressure 
of gravity shall be employed in generating 
motion in the water; or it may be made to 
move so slow as to require a wheel of such 
magnitude to hold the water, that almost the 
whole of the force shall be exhausted in gene- 
~ rating motion in the wheel, and in overcoming 
the friction of the machine; but the whole 
moving force is, nevertheless, in both cases 
exerted, and it is immaterial to the principle 
of its proper measure, whether it be applied in 
generating motion in the water, or in the 
machine,—in overcoming friction, or in pro- 
ducing any other known effect of moving force. 
Y 
