446 Memoir of James Waif 3 Esq. F.U.S. 



when he was in London, he said it was true, but that he had 

 seen De Pronv, who had made some sort of an apology, or en- 

 tered into an explanation. Mr. Watt did not appear to wish to 

 enter on the subject ; but, with great deference to his opinion on 

 that point, we think tlie injury neither admitted of explanation 

 nor apology of anv sort. It was a wilful and gross misrepresen- 

 tation, and it can never pass for any thing else. What adds to 

 the injustice is, that M. deProny could not write a history of the 

 invention for which he had not materials, though he has con- 

 trived to fill two quarto volumes with his account of that machine. 



An injury done at the expense of truth deserves to be noticed 

 in a way rather different from that in which Mr. Watt noticed 

 the act committed by M. de Prony. We, however, go further, 

 and say, that it is in some degree a national affair, and strongly 

 suspect that it was in order to rob England, and not to rob Mr. 

 Watt of the invention that the merit was given to the Perriers. 



It is to be hoped, that as both Mr. Boulton and Mr. Watt left 

 sons, thev will cause this matter to be set to rights. 



The steam-engine, notwithstanding the great improvements 

 made, was oidy hitherto (in 1780) employed to raise water, and 

 when intended to give motion to mill works, the water raised was 

 made to turn an overshot wheel in the ordinary way ; but this 

 was attended with a great loss of power. 



We now come to the second great improvement made on the 

 steam-engine by Mr. Watt — that improvement which led directly 

 to the revolution that has taken place in the mechanical world. 



To convert a reciprocating motion into a rotative one, as is 

 done with the common spinning-wheel, and in turning lathes 

 moved by the foot, merely by means of a crank, might appear to 

 be a verv simple, matter. In short, it might appear to be an af- 

 fair alreadv settled ; yet this application of power on the great 

 scale gave rise to some very curious circumstances. 



During the summer of 1780, Mr. Watt set seriously about ap- 

 plying the engine to the turning mill work, which he intended to 

 do bv means of a crank. This is a mistake. The most compli- 

 cated mode did not occur first. The application of the crank in 

 the manner of the conmion turning lathe was Mr. Watt's first 

 idea. But, to use his own words, as the rotative motion is pro- 

 duced in that machine by the impulse given to the crank in the 

 descent of the foot only, and behoves to be continued in its ascent 

 by the momentum of the wheel, which acts as a fly, he was un- 

 willing to load his engine with a fly heavy enough to continue the 

 motion during the ascent of the piston, and therefore proposed 

 employing two engines, acting upon two cranks fixed on the 

 same axis at an angle of 120" to each other, and a weight placed 

 upon the circumference of the fly at the same angle to each of 



the 



