'Regnter's new Potixder^Proof. 39^ 



purpofe. I fliall, therefore, only obferve, that trials of gun- 

 powder on a large fcale are always the beft ; but as fuch 

 experiments require certain kinds of apparatus and conve- 

 niences which are not always at command, a fmall powder- 

 proof, in the form of a piftol, the blaft of which drives a 

 final! toothed or turned wheel that rubs againft a fpring, 

 and is moved through a greater or fmaller fpace according 

 to the ftrength of the powder, has been long ago adopted 

 and brought into common ufe. This machine, however, is 

 very defective in regard to the refults wliich it gives, and caa 

 ^e of no utility when an abfolute or approximate indication is 

 required of the relative ftrength of a given weight of powder 

 intended for fire-arms, which are loaded with quantitia 

 •determined in this manner: thefe proof-inftruments have 

 indeed an arbitrary graduation, and their friction varies ac- 

 cording to the itrength of the fpring and the cleannefe of 

 the mechanifm. 



To obviate thefe Inconveniences, I made feveral expeiir 

 ments, which led me to a more valuable and accurate prin- 

 ciple ; and, with fome variations, I at length fitted a fmaU 

 brafs cannor> to the fpring of a common weighing inllrn- 

 ment. By this application I was enabled to weigh tlie 

 effort of the blaft, and confequently obtained a comparative 

 method of afccrtainlng its a£tion. This inftrument is at- 

 tended likewife with this valuable advantage, that it afts 

 without fri6lion. Its graduation is accurately determined, 

 becapfe it expreflcs the weight which fcrved for that puf- 

 pofe ; and it may likcwife be applied for weighing fuch 

 bodies as come within the limits of its fcale. 



A perfpcdiive view of this inftrument is reprefented, 

 (Plate IX. fig. 1.) BC is a fpring bent fo as to form an 

 angle ; D a fmall brafs cannon capable of containing ck- 

 aitly 15 ! grains of fine gunpowder ; E the graduai-^d arc, 

 fach divifion of which is nearly equal to a' pounds aver- 

 ilupoiff, and terminating in a fcrew that fcrves as a breech 

 pin to the c;innou, F is a cap which niay be confidcred as 



