MOVING KORCK. 
water, by springs or any other kind of motive power. Machines 
of this sort, owe their origin and improven'.ent to other sources ; 
it is from long experience of repeated trials, errors, delibera- 
tions, corrections, continued through the lives of individuals, 
and by successive generations of them, that sciences, strictly 
called practical, derive their gradual advancement from feeble 
and awkward beginnings, to their most perfect state of excel- 
lence*.” 
But he has, in this instance, I apprehend, pressed his argu- 
SiTiPaton h.is 
st>i-wn the con- 
(r.ry. meat rather too far; and he is quite at variance with Mr. 
Smeaton, who h.as pointed out many inconsistencies in theore- 
tical conclusions, which have been carried into practice with 
most injurious elTectsf. 
Advantages of It cannot be doubted, tliat ingenious men, of rare natural 
inactical iren f’''>(5owments, have, without any scientific aid, accomplished 
wonders in the invention and improvement of machinery. But 
how’ can it be supposed that these men could have derived no 
assistance from a clear and sound knowledge of the principles 
of mechanics r Every new combination presented to tiieir 
minds must have involved them in new, and repeated labours 
to ascertain its effects ; and these labours must have frequently 
terminated in a conviction, that their time and pains had been 
« Treatise onitcctil. and Rotat. Motion, p. 381. 
t See rUiiosoplik-al Tran>aetious, vol.6n, part '^d. p. 4.52, See. and 
the follow ill” note, p. 454. “ Ikiidore (Arch. Hydr.) greatly paefers 
the appl-catinn of water to an uiicer.shot mill, iiisti ad of overshot ; and 
attempts to dcnioiistrate, that water, applied undershot ; will do six 
times more execution than tl;c same applied overshot. .See vo>. 1. p. 
v.'86. While Desajeliers, endeavouring to invalidate what had been 
acivaneed by lie.iiilore, and greatly preferring an overshot to an uudci- 
siiol, rays, (.Annotarions on Lecnire l”. vol. 2 p. .5.52.) that from his 
own eitperience, a well made over.-hot mill, ground as mneh corn in 
the same time, with ten times less water so that betwixt I’elidore and 
Poagulieis, iiere is a difference of no less than 60 to i.—Smealoh. 
F.ach of these aufiior.'! has been considered by many a.s the best 
aiiUioriiv for practical men ; and ibejr various inconsistent rulc.s have 
often be( 11 adopted, in the construction of expensive machines, in this , 
cduulry, as vvi 11 as on the eoiitineDt. 
wasted 
