dmluJUoH of Gunpowder in a Clofjd Veffcl, ^gr 



fair M-eatlier, and between the hours of nine and twelve in thq forenoon, and two and five 

 in flic afternoon ; but the barrel was always charged, and the exf.emity of the bore clofed 

 by its leather ftopper in the room where the powder was weighed. In placing the barrel 

 upon the block of (lone, great care was taken to put it exadly under the centre of gravity 

 of the weight employed to confine the generated elaftic vapour. Upon applying the red- 

 hot ball to the vent tube, and fixing it in its place by its lever, which fupported it, theexplo- 

 fion very foon followed. 



When the force of the generated elaftic vapourwas fufficicnt to ralfe the weight, the ex- 

 plofion was attended by a very (harp and furprifingly loud report ; but when the weight was 

 not raifed, as alfo when it was only a little moved, but not fulEciently to permit the leather 

 ftopper to be driven quite out of the bore, and the elaftic fluid to make its efciipe, the report 

 was fcarcely audible at the distance of a few paces, and did not at all refcmble the report 

 ■which commonly attends the explofion of gunpowder. It was more like the noife which 

 attends the breaking of a fmall glafs tube, than any thing elfe to which it could be compared. 

 In many of the experiments in which the elaftic vapour was confined, this feeble report at- 

 tending the explofion of the powder was immediately -followed by another noife totally dif- 

 ferent from it, which appeared to be occafioned by the falling back of the weight upon the 

 end of the barrel after it had been a little raifed, but not fufficiently to permit the leather 

 ftopper to be driven quite out of the bore. In fome of thefe experiments a very fmall part 

 only of -the generated elaftic fluid made its efcape ; in thefe cafes the report was of a pe- 

 culiar kind ; and though perfe£lly audible at fome confiderable diftance, yet not at all refem- 

 bling the report of a muflcet. It was rather a very ftroiig fudden hiffiiig, than a clear, 

 diftindt, and (harp report. 



Though it could be determined with the utmoft certainty by the report of the explofion, 

 whether any part of the generated elaftic fluid had made its efcape ; yet for Hill greater pre- 

 caution, a light collar of very clean cotton wool was placed round the edge of the fteel 

 henrifphere, where it repofed upon the end of the barrel, which could not fail to indicate, by 

 the black colour it acquired, the efcape of the elaftic fluid, whenever it was (Irong enough 

 to raife the weight by which it was confined, fufficiently to force its way out of the 

 barreL 



Though the end of the barrel at the mouth of the bore was covered with a circular plate 

 cf gold, in order the better to defend the mouth of the bore againft the efi'ciSls of the corro- 

 five vapour; yet, this plate being damaged in the courfe of the experiments (a piece of it 

 tcing blown away), the remainder of it was removed, and it was never after thought ne- 

 ceflary to replace it by another. When this plate of gold was taken away, the length of the 

 barrel was of courfe diminlflied as much as the thicknefs of this plate amounted to, which 

 Vas about -^i^th part of an inch ; but inorder that even this fmall diminution of the length 

 of the barrel might have no efl^ed on the refults of the experiments, its bore was deepened 

 yj^th of an inch virhen this plate was removed, fo that the capacity of the bore remained the 

 fame as before. 



After making ufe of a great variety of expedient':, the beft and moft convenient method 



cf clofmg the endof the bore, and defending the flat furfacc of the fiecl hemifphcre from 



the corroding vapoiys, was found to be this : Firft, to cover the' end of the bore with a 



circular plate of thin oiled leather ; then to lay upon this » very thin circular pl.ite of 



4 lianimercd: 



