10 On Mathines in Generate 



and if T am not deceived, it is sufficient of itself, an4 inde- 

 pendently of every other mechanical principle, to resolve all 

 the pHFticular cases to be met with. 



I easily draw from this equation a general principle of 

 equilibrium and movement in machines properly so called, 

 and from the latter naturally flow o>her principles more or 

 less general, several of which are already known and very 

 celebrated, but which have been hitherto eirtier inexactly or 

 vaguely explained, rather than rigorously demonstrated. 



Without departing from general principles, I have united 

 in a scholium, and as clearly as possible, the most useful 

 remarks for practice, and which, ^om their importance^ 

 appeared to me to merit a par:icular development. Every 

 person repeats, that in machines in movement, we always 

 lose in time or in velocity what we gain in power; but after 

 perusing the best elements of mechanics, which seem to be 

 the true place where the proofs and explanation of this prin- 

 ciple should be found, — Is its extent or even its true, signi- 

 fication easy to seize ? Has its generality, with most readers^ 

 that irresistible evidence which should characterize mathe* 

 rnatical truths ? If they exhibit this striking Conviction, 

 ought we not to see mechanics instructed in th<jse works, 

 incessantly, renounce their chimerical projects ? Would they 

 not cease to believe, in spite of every thing that has been 

 taught them, that there is something of magic in niachines ? 

 The proofs given .them of the contrary only extend to 

 simple machines : now they do not think these capable of 

 any great effect, and they cannot be brought to believe that 

 it must be the same in every case imaginable; they only 

 speak of that where there are solely two forces in the system^ 

 and they are contented with an analogy : this is the reason 

 why these mechanicians always hope that their sagacity will 

 make them discover some unknown resource, some ma- 

 chine which is not comprehended within the ordinary rules; 

 they think themselves so much the more certain of meeting 

 with it, the further they remove from every thing which 

 seems to have any relation with machines in use, because 

 ihey itnagine that the theory established with respect to the 

 latter, cannot be extended to constructions which do not 



seem 



