40a Defcript'ion and tlfe 



T>, a fmall fteel fupport, adjufted like the former to th* 

 other branch of the fpring, and having a cleft towards its 

 upper extremity to receive freely a fmall copper lever E t 

 which is kept in its place by a fmall fteel pin a. The whole 

 of this mechanifm is feen of its full fize at H. 



F, a fteel index, very light and elaftic, fixed upon its axis 

 by a fcrew in the centre of the brafs femicircle. This index 

 has- a fmall bit of leather or cloth glued upon the fmall cir- 

 cular part G, in order to render the friction on the plate 

 eafy, uniform, and almoft infcnfiblc. It is to be obferved, 

 that this index is terminated by a double point, adapted to 

 the divifions on both the femicircular arcs. The firft, di- 

 vided into myriogrammes and points, cxprefling ten pounds 

 de marc, ferves for all experiments which oblige the fpring 

 to be elongated in the direction of its greater axis, as is the 

 cafe in trying the ftrength of the reins ;. in a word, for all 

 trials where it is nccelfary to draw the fpring by the two 

 ends. The fecond, divided into kylogrammcs and points, 

 exprefling pounds de marc, is deftined for experiments which 

 comprefs the two fides of the fpring, as in trying the force 

 of the hands. 



J, a fmall plate of brafs which covers the mechanifm, 

 to prevent it from being injured. This fmall plate has on it 

 alfo a divided are, the degrees of which correfpond with thofe 

 of the firft arc of the machine ; and by the play of a fmall 

 index b, which is under the plate, the movements of the 

 fpring may be afcertaincd. 



K, an aperture in the covering plate, through which may 

 be introduced a fmall turnferew, for the purpofe of tighten- 

 ing or eafing the index as may be necefiary. 



L, a pallet of brafs, with a fcrew, having a cap like that 

 on the needle of the mariner's compafs, in which the lower 

 pivot of the lever, that pttfhes round the index or handle, is 

 made to play. This pallet, sCeling as a fpring, yields to any 

 fudden (hock, and prevents the dc rangementbf the mechanifm. 



M, a 



