Memoir of James Watt, Esq. F.R.S. 445 



From the depth of the pit, the size of the pumps, and num- 

 ber of strokes of the engine, they knew the quantity of coals that 

 was necessary either for the old engine or the new. They there- 

 fore had onlv to estimate the quantity of coals saved in making a 

 certaui number of strokes, and according to the price they knew 

 what was the value saved. A counter, to tell the number of 

 strokes, inclosed in an iron box, was fixed on the beam of each 

 engine ; there were two different sashes to the box, and two keys 

 kept bv the proprietors and two by Roulton and Watt, who had 

 a traveller that went round to the different engines from time fo 

 time, and the counters being examined, the money was paid ac- 

 cording to the number of strokes. 



Men with less perseverance or less genius for overcoming dif- 

 ficulties, would have failed in this enterprise; but still notliing 

 eould equal their patience and continued attention to the business. 

 In relating the important facts concerning so important an in- 

 vention, we must not, however, omit to state some mistakes that; 

 were committed, for which it is not easy now to account. 



In 1779 the elder brother Perrier came over to Birmingham 

 from Paris to get an engine for the supply of that capital with 

 water, and the whole was sent over with the permission of go- 

 vernment. The engine at Chaillot was that then sent, after which 

 the Perriers made several other engines, and, to do them justice, 

 they executed them very well : but we beg the reader to attend 

 most particularly to the fact, that the first engine erected at Paris 

 was made at Birmingham, and sent over for IM. de Prony, a 

 French engineer, and a man of merit, who wrote a History of the 

 Improved Steam-en2,ine, which invention he gives to the Perriers, - 

 never once mentioning the name of Mr. Watt. The work is in 

 two volumes in quarto. — M. de Prony is a man of merit, and well 

 known to the literary and scientific world, and it is an injustice 

 to Mr. Watt and his country that ought to be recorded. 



Since we are led to this subject we must be permitted to add, 

 that we were acquainted with the Perriers — that the elder bro- 

 ther was not a mechanic at all, and the other merely a good prac- 

 tical workman. 



It is not very ea;y to conceive how M. de Prony could have 

 committed so flagrant an injustice, because he must have knowa 

 better, and therefore ought to take shame to himself, as every 

 man ouglit who imposes falsehoods on the world for trutli, which 

 is in itself a great (hsgrace, but doubly so when by that false- 

 hood he deprives a man of merit of the credit due to him, and 

 gives it to another, who has not only no claim, but who was not 

 capable of any invention of the sort. 



Mr. Watt was too inoffensive a man to attack de Prony ; and 

 vvhcti the injustice done was mentioned to him in 1810 or ISl 1, 



when 



