Moving Force. 107 
mere scientific explanation of the phenomena, 
it is said, can be of little importance to prac- 
tical men. 
On this point, however, Mr. Smeaton’s ob- 
servations merit particular attention. He 
says, in reference to mistaken notions about 
the measure of force, “that not only himself 
and other practical artists, but also some of the 
most approved writers, had been liable to fall 
into errors, in applying the doctrines of force 
to practical mechanics, by sometimes forget- 
ing or neglecting the due regard which ought 
to be had to collateral circumstances. Some 
of these errors are not only very considerable 
in themselves, but also of great consequence to 
the public, as they tend greatly to mislead the 
practical artist in works that occur daily, and 
which require very great sums in_ their 
execution.” * 
Notwithstanding Mr. Smeaton’s excellent 
experiments and observations on this subject, 
exhibiting much want of agreement between 
the theory usually given, and the practical 
results, the mechanical principles of force 
continue to be treated nearly as before; and, 
I believe, we are not without recent instances 
of errors similar to those which he has noticed. 
* Philosophical Transactions, vol. 66. part 2d, p. 452. 
Q 2 
