404 T)efcr\ftion anil Uff, &fc. 



recollected, that the lower arc of divifion, divided into kyfo-' 

 grammes, is that which ferves to exprefs the force of IH 

 hands, and of all the actions which prefs the two fiqK 

 of the fpring. The ftrength of the hands may alfo he tries' 

 one after the other ; and if an account be kept of the de- 

 gree of preffure of the right hand, and then of the left, and 

 thefe two funis be added together, it will be found that the- 

 fum-total is, in general, equal to the ftrength of both the 

 hands when acting; together". 



To try the ftrength of the body, or rather the reins, the 

 perfon mull place his feet on the bottom part of the rack O ; 

 one of the ends of the fpring is then to be placed in one of 

 the hooks of the rack ; and the hook P is to be put into 

 the other end. In this pofition the body is perpendicular ; 

 the fhoulders only being inclined a little forwards, to be 

 able, in throwing back the body, to pull the fpring with 

 all the force which a perfon is capable of exerting. In this 

 fituation, reprefented by S, a man may raife a great weight 

 without being expofed to thofe accidents which might be 

 occafioned by an effort made in a more conftrained pofition. 



Nothing can be more convenient than this dynanomcter 

 to afcertain and compare the ftrength of horfes and that of 

 all draught animals. Figure T (hews, in a fufficient man- 

 ner, the difpofitions neceffary for experiments of that kind. 

 The trials I made on this fubjeet are not extenfive ; but as 

 they were conducted with care, they may ferve to give a very 

 juft idea of the abfolute force of horfes of middling ftrength. 

 For this purpofe I employed four horfes of middle fize, in 

 good health and well-conditioned, which were fubjected fe- 

 parately and in fucceffion to the fame trial. The firft drew 

 equivalent to 36 myriagrammes ; the fecond 38^ ; the third 

 a6~J-; and the fourth 43. The fum of all thefe is 144 my- 

 riagrammes ; and if we take the mean of this fum, we 

 mall have, for the ftrength of ordinary horfes, 36 myria- 

 grammes, or ^6 pounds de marc. 



7 XH. Me, 



