H'lftory of AJlronomy for the Year 1799. ni 



In the American war with d'Eftaing in 1777 and i-778j ^is 

 health was impaired, but he ftill employed himfelf in ufcful 

 labours. In 1778 he introduced into altronomy and the 

 navy multiplying circles, invented by Tobias Mayer, of the 

 importance of which no one had before been fenfible. He 

 brought them to perfeftion, and by thefe means rendered an 

 efl'ential fervice to aftronomy and navigation. 



In 1793 he invented inftruments and methods for obferv- 

 ing the length of the pendulum, with a precifion before un- 

 known; and metallic rules for meafuring bafes, intended to 

 give the real length of the meridian. Theie inftruments 

 were of great utility for that great and important labour. As 

 refractions were neceflary in this labour, he made experi- 

 nients and theoretical refearches worthy of a great geome- 

 trician. They are preferved among his papers, atid a large 

 memoir by him is ready to be printed. 



He caufed to be calculated at his houfe, and at his own. 

 expence, the logarithms of the decimal parts of the circle, 

 according to the new divifion into 400 parts ; and defrayed 

 the expences alfo of printing. The publication of it is im- 

 patiently expefted. 



I have publiflied in my Abridgement of Navigation his 

 new method for gauging veflcls, together with the tables. 

 He was infpctitor of the dock-yards : in this fituation he was 

 yfcful, aiid Government had the greateft confidence in hi* 

 talents. 



C. Lemonnier died at his feat at Herils, near Bayeux, on 

 the 2d of April. He had been loft to us ever fmcc the 10th 

 pf November 1791 : three years ago I cave an account of his 

 iifcful labours, but the lalt epoch of this memorable life 

 ought to be confecrated in the prefent hiftory. I wifhed to 

 infert in the firft volume of the Hijhire Celfjle, now printing, 

 a part of the obfervations of my illuftrious maftcr: nothing 

 would have been fo dclirable as to render this tellimony to 

 his memory, which would have been at the fame time a tef- 

 timony of my gratitude; but I was not allowed, notwith- 

 (landing my zeal and entreaties, to have any communication 

 with his manuicripts : I do not know what will become of 

 ihcm in hands foreign to aflronomy, and which focm as in- 



dilTcrcut 



