tSl^] RYDUOSTATIC BALANCE. S^9 



shorter end ^^ iilcr, and ^vith aa enlvari^ciiient at the ex- 

 iremity. Tiie upper edge of each limb^ is rectUiiicar^ 

 sniid free from uotclies, for the sake of ac€iin\cj ia aj- 

 jiisthig the weights. 



The shorter end is undivided ; but on the longer is 

 inscribed a scale, of which every division, reckoning 

 from the^ extremity of the lever^ is marked with ti 

 number, whicli is the quotient of the length of thi^ 

 wiiole scale, divided by the distance of tlie divisioa 

 from the end. Thus at half the length is marked thi^ 

 ^umber 2, at one-third, 3, at one-fourtli, 4, &c. Alsof 

 at two-tliirds the length is marked one and a lialf, at 

 twotfiiihs, two and a Inilf, &c. And so of all tlio 

 fractions, suiUcibriily minutely. These numbers ex- 

 lend as liigh as the spechlc graviiy of platlna ; — thts^ 

 pivot of the instrument represents ualtj, and a notc]x 

 is made at the farther end. 



lii using tills ii|struraent, any convenient welglit is 

 suspended by a hock from the notch at the end of the 

 iTcaU. The body under examination is to be suspend- 

 ed to the other end by a horae-hair, and slid along till 

 an equilibrium i^ produced. It is then, vv ithout alter-. 

 ing its situation on the beam, to be bnmersed in water^ 

 ^and balanced a second time by slidiiig the weight. 

 The hook of the latter then ma; l^s the spccllic, gravity 

 i^n the scale. 



The demonstration of this is very simple. Tlic la- 

 ^trumeni being supposed in equiiibriiini, and B 1) (^ee 

 %.ire) and tlie weiglit of tlie counterpoise being ctvn- 

 ^lunt, the weight of ll:e body varies as t'ie tlisian( e of 

 t|iti^uai^tcr|)-ise fr:>m IJ; by i^ie; cowiUiiOji priiicipic of 



