MOVING FORCE. 
177 
water ; or If, after being comrminicnted to the water, ibe pres- Cases of diffi- 
8ure of the steam be not wholly applied in producing the i»* IJocnin' !'of 
tended effect, the loss must be owing to practical imperfections movm^ lorce. 
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, iti practice nevei be completely trans- 
ferred from one given object to another, yet tl-.eie can be no 
doubt of the real existence of both the heat and the force in 
their full (]uantities ; and we can form no iilea of the portion 
of time being limited in which the one must bo evolved, or the 
other transferred. 
A water wheel may be made to move with a velocity so 
great, that almost the vshole pressure of gravity shall be em- 
ployed in generating motion in the wattr ; 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 generating motion in the wheel, and in overcoming the fric- 
tion of the machine ; but the*whc)le moving force is, never- 
theless, in both cases, exerted ; and it is immaterial to the 
: principle of its proper measure, whether it be applied in gene- 
rating motion in lire water, or in the machine, in overcoming 
! friction or in producing any other known effect of moving 
force. 
Jf it appear that I have insisted too much on this part of my 
■subject, it should be recollected, that many of the objections 
w hich I have been endeavouring to meet, apply not only to the 
particular cases under consideration, btut generally to the whole 
question at issue. I must acknowledge, too, that I have felt 
more than ordinary solicitude that the experience and the con- 
clusions of one who has long been looked up to, in tliis country, 
■as the father of civil engineers, should be duly appreciated. 
But it is not necessary, I .apprehend, to resort to complicated 
vases for the purpose of examining the points in question. If 
the two first cases which I have stated w ere once distinctly 
explained and agreed upon, no difficulty would remain in ex- 
plaining their various and multiplied applications in machinery. 
VoL. XXXVI.— No. 167. O Although 
