112 On the Measure of 
But he has, in this instance, I apprehend,’ 
pressed his’ argument rather too far ; and he is 
1, quite at variance with Mr. Smeaton, whio has 
_-—- pointed out many inconsistencies in theoretical. 
conclusions, which ‘have been carried’ into 
practice with most injurious effects. * 
It cannot be doubted, that i ingenious men, 
of rare natural endowments, 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 
es a 
* See Philosophical Transactions, vol. 66, part 2d. p. 452, 
&c. and the following note, ps 454. “ Belidore (Arch. Hydr.) 
greatly prefers the application of water to an, undershot 
mill, instead of overshot; and attempts to demonstrate, 
that water, applied undershot, will do six times more exe- 
ae ug ition than the same applied overshot. See vol. 1. p. 286. 
ThileDe saguliers,endeavouring to invalidate w bat had been 
: . I s088 by Belidore, and greatly preferring an overshot 
. to an undershot, says, (Annotations on Lecture 12. vol. 2. 
p- 532.) that from his own experience, “ a well-made over- 
shot mill, ground as much corn in the same time, with ten 
times less water ;” so that betwixt Belidore and Desaguliers, 
here. is a difference of no less than 60 to 1.—Smeaton. 
Each of these authors has been considered by many as - 
the best authority for practical. men ; and their various in- 
consistent rules have often been adopted, in the construction 
of expensive machines, in this country, as well as on the 
continent, 
