122 Experiments to dete^'miiie 



little moved, but not sufficiently to permit the leather' 

 stopper to be driven quite out of the bore, and the 

 elastic fluid to make its escape, the report was scarcely 

 audible at the distance of a few paces, and did not at all 

 resemble the report which commonly attends the explo- 

 sion of gunpowder. It was more like the noise which 

 attends the breaking of a small glass tube than anything 

 else to which I can compare it. 



In many of the experiments' in which the elastic 

 vapour was confined, this feeble report attending the ex- 

 plosion of the powder was immediately followed by an- 

 other noise, totally different from it, which appeared to 

 be occasioned by the falling back of the weight upon 

 the end of the barrel, after it had been a little raised, 

 but not sufficiently to permit the leather stopper to be 

 driven quite out of the bore. In some of these experi- 

 ments, a very small part only of the generated elastic 

 fluid made its escape ; in these cases the report was of a 

 peculiar kind, and though perfectly audible at some con- 

 siderable distance, yet not at all resembling the report 

 of a musket. It was rather a very strong, sudden hiss- 

 ing, than a clear, distinct, and sharp report. 



Though it could be determined with the utmost cer- 

 tainty, by the report of the explosion, whether any part 

 of the generated elastic fluid had made its escape, yet for 

 still greater precaution a light collar of very clean cot- 

 ton wool was placed around the edge of the steel hemi- 

 sphere, where it reposed upon the end of the barrel, 

 which could not fail to indicate, by the black color it ac- 

 quired, the escape of the elastic fluid, whenever it was 

 strong enough to raise the weight by which it was con- 

 fined sufficiently to force its way out of the barrel. 



Though the end of the barrel, at the mouth of the 



