C. Paul's new Steel-Yard. 41 j 



the beam marked water on the fide F of the beam, and the 

 fmall one at the divifion O, that is to fay, the extremity. 

 When the apparatus is thus prepared, you fill ajar with the 

 liquid, the fpecific gravity of which you wifh to afcertain ; 

 iufpend the bail II to the hook of the ftecl-vard, and immerfe 

 it Into the liquid till it rife exactly above the ring from which 

 the ball hangs, obferving the temperature, and difengaging 

 carefully all the air bubbles that may adhere to the ball; then 

 remove the fmall weight to the divifion O at the end of the 

 beam, and convey the large one as far as that divifion, pre- 

 ceding that where the weight of the ball would raife the beam ; 

 and afterwards move the fmall weight as tar as the divifion 

 where the equilibrium will be reftored, the beam beincr hori- 

 zontal. Mark the divifion at which th% large weight is 

 found, and add two cyphers ; to this number add the indica- 

 tion immediately refulting from the pofition of the fmall 

 weight, and the fum of thefe two numbers gives the fpecific 

 gravity of the liquid, or its ratio with the weight of diftilled 

 water to a ten thoufandth part. 



The balloon N is deftined for trying the weight of any- 

 given kind of gas compared with that of atmofpheric air, in 

 the following manner : — The weight entitled ear tare is ar- 

 ranged in fuch a manner that when placed in the notch, 

 feen at the extremity of the beam beyond the divifions to- 

 wards B, it forms an equilibrium with the balloon exhaufted 

 by the air-pump and fufpended from the hook of the fkel- 

 yard. If the fteel-yard is not then in equilibrium, it is a fio- n 

 that the inftrument is deranged, or that the vacuum is not 

 perfect. The air, the relative weight of which in regard to 

 atmofpheric air you wifh to afcertain, is to be introduced into 

 the balloon, and the weight marked air is to be moved alongthe 

 beam. The divifion at which it flands when an equilibrium 

 is produced will indicate, in hundredth pirts of the weight 

 ot the volume of atmofpheric air that could be contained in 

 the balloon, the weight of the gas aftually inclofed in it. 



This 



