INVENTION OF CHRONOMETERS, &C. 289 



In the Histoire de la Mesure du Temps* the invention of Berthoud as- 



the detached escapement is ascribed to three different persons, mention o/the 



who accomplished it separately, and upon distinct principles, detached es- 



without any communication with one another; P. le Roy? leRoy, Mudge' 



T. Mudge, and the author, F. Berthoud, himself. We have and himself. 



already noticed the labours of the two former, and it remains 



for us to state what right the last may appear to have to the 



honour he claims. The title of P, le Roy to priority cannot be 



invaUdated, and what F. Berthoud has written upon the subject 



is of so much later date, and his ideas seem so closely derived 



from those of the preceding author, that it would not be fair 



to grant him the share he assumes in point of originality on 



this occasion. Berthoud published his Essai sur riIorlogerie'Re^^ons,sh.evf. 



in 1763; but not one word is to be found in it, respecting the].'^yy^\gg^^ 



principle of the detached escapement, though P. le Roy had claim to the 



made it publicly known fifteen years before. This silence 



or omission in a treatise of two volumes in quarto, respecting 



a construction so remarkable, appears to be inconsistent with 



the subsequent pretensions of the author ; and this circumstance, 



at least, must prevent our supposing that he had applied with 



miach attention to the subject. It was not till 1773 that Ber- He took no 



thoud took notice of the detached escapement, in his Traitedes detached es^ 



Horloses Marines, where he describes several constructions of capement till 



1773 

 that kind, giving them as the result of his own inquiries, upon 



which he says he had been engaged, ever since the beginning of 

 his labours upon timekeepers for sea. In that work, Berthoud 

 also states,! that in 1754 he made a model of a detached es- 

 capement, which he shewed to M.Camus, to be presented to the 

 Academy of Sciences, when that learned gentleman told him, 

 that M. Dutertre, the father, had had the same idea before. 



It might have been of service to him, to have been at the Berthoud 

 saJB^ time reminded of what P. le Roy had done in the same tioiiing Peter 

 -way ; for the name of that artist is, in the whole, so studiously ^^ ^^J- 

 avoided, as to raise a suspicion of want of candour in the wri- 

 ter, who, on several occasions, was the declared rival of that 

 great mechanic. It may also be remarked, that F. Berthoud 

 was, even at that time, so far from judging properly of the de- 

 tached escapement, that he concludes his book on marine time- 



* pp. 24 and 25. f p. 97, note b. 



Vol. XIV.~~AuGusT, 1806. Pp keepers, 



