^do Uefcription and tffe 



machines were neceflary, each fuited to the part required to 

 be tried. They were acquainted alfo with the dynanometer 

 of Cit. Leroy of the Academy of Sciences at Paris. It 

 confifted of a metal tube ten or twelve inches in length, 

 placed vertically on a foot like that of a candleftick, and 

 containing in the infide a fpiral fpring, having above it a 

 graduated fliank terminating in a globe. This ihank, toge- 

 ther with the fpring, funk into the tube in proportion to 

 the weight acting upon it, and thus pointed out, in degrees, 

 the ftrength of the perfon who preffed on the ball with hit 

 hand. 



This inftrument, though ingenious, did not appear fuffi- 

 cient however to Butfon and Gueneau ; for they wilhed not 

 merely to afcertain the mufcular force of a finger or hand, 

 but to eftimate that of each limb feparately, and of all the 

 parts of the body. I (hall not here give an account of the 

 attempts I made to fulfil the willies of thefe two philo- 

 ibphers, but only obferve, that in the courfe of- my experi- 

 ments I had reafon to be convinced that the conft ruction of 

 the inftrument was not fo eafy as might have been expected. 

 Befides the ufe which an enlightened naturalift may make 

 ' of this machine, it may be poifible to apply it to many 

 other important purpofes. For example, it may be em- 

 ployed with advantage to determine the ftrength of draught 

 cattle ; and, above ail, to try that of horfes, and com- 

 pare it with the ftrength of other animals. It may ferve 

 to make known how far the afliftance of well-conftruct- 

 ed wheels may favour the movement of a carriage, and 

 what is its vis incrine in proportion to the load. We might 

 appreciate by it, alio, what refiftance the Hope of a moun- 

 tain oppofes to a carriage, and be able to judge whether a 

 carriage is fufficiently loaded in proportion to the number 

 of horfes that are to be yoked to it. In the arts, ic may be 

 applied to machines of which we with to afcertain the re- 

 liftance, and when we are defirous to calculate the moving 

 force that ought to be adapted to them. It may ferve, alio, 



M 



