184 Relation of the Laws of Mechanics to Perpetual Motion. 
But the inventor, though he may not boast of theory on his 
side, has that which, is of far greater importance, the support of 
fact. His machine goes. . So does a time piece go. It may be 
made to go, for a whole year together, without being wound up. 
But this is not perpetual motion. Ina clock, a force is wanted 
__ «to supply the loss it friction. If the ieediien is nicely con- 
a -- structed, this loss may be very small. A large weight may fur- 
-. - nish the requisite supply, for a long time, without coming to the 
 —..- ground.. But when it has descended as far as it can, its power is 
exhausted, and the motion ceases. To determine from trial 
whether any particular machine has an unfailing principle of ac- 
oe) OF months, perhaps, to exhaust ee moving en in merely over- 
-";~ coming the friction. But let it be required to do something 
_~ . more. Instead of merely sic: pie it be applied to some practi- 
2 Peal p purpose. Let it be employed, for instance, in the grinding of 
Ee r the sawing of timber. In proportion as the resistance 
eased, the time of its action will be shortened, if, like other 
apes, it SRT os on a renewed application of force from 
ut if it possesses a perpetuating principle, this may 
«% feta ate sa part of theloss of momentum which pro- 
ge nthe resistance of the 
: grain or the timber; as well as 
lat whielf'is owing to friction‘and the air. In this manner, the 
: may be brought to’ the test of experiment, in a very 
= 
' Pret to any supposed invention, in years past } of an 
strument for perpetual oo we oa ve only to inquire, 
hether it is now in operation, in our manufacturing establish- 
mboa ts, ‘and our railroad cars are actually moved™ byt. 
ca 
mi Panos cou not long be 
oul coveted al: ctl 
to “0 
ents of*every description ; whoa er our mills, and forges, our - 
‘eam ‘An ’ 
0 produce’ so phe oe revolution in ~ a 
ohee Yonfin ed to % 
