460 Con^ujtion of Gunpowder in a Cle/ed Vtjfd. 



were exaiTlly oppofitc to each other, and on oppofite fides of the chamber, the axes of their 

 bores were in the fame right line. The fliorteft of thcfe tubes, which projcifUd 1,3 inch 

 beyond the external furface of the barrel, was clofcd at its projeiiting end ; or rather it was 

 not bored quite tlirough its whole length, r^ths pf an inch of folld metal being left at its end, 

 which was rounded off in the form of a blunt point. The longer tube, which projcQeJ 

 2.7 iiKhes beyond the furface of the barrel on the other fide, and which fcrvcd for intro- 

 ducing the powder into the chamber, was open ; but it could occafionnlly be clofcd by a 

 ilrong fcrew furniflied with a collar of oiled leather which was provided for that purpofc. 

 'J he method of making ufc of this inftrumcnt was as follows: Tlie barrel being laid down, 

 or held in a horizontal pofition with the long tube upwards, the charge, which was of the 

 very befl fine-grauied glazed powder, was poured through this tube into the chamber. In 

 doing this, care muft be taken that the cavity of the fhort tube be completely filled with 

 powder •, and this can beft be done by pouring in only a fmall quantity of powder at firll, 

 and then, by ftriking the barrel with a hammer, caufe the powder to defcend into the fliort 

 tube. When, by introducing a priming -wire through the long tube, it is found tiiat the fliort 

 lube is full, it ought to be gently prefled together, or rammed dovirn by means of the prim- 

 ing-wire, in order to prevent its falling back into the chamber, upon moving the barrel out 

 of the horizontal pofition. The Ihort tube being properly filled, the reft of the charga 

 may be introduced into the chamber, and the end of the long tube clofed up by its fcrew. 



More effe£\ually to prevent the elaftic fluid generated in the combullion of the charge 

 from finding a paflage to efcape by this opening after the charge was introduced into the 

 chamber, the cavity of the long tube was filled up with cold tallow, and the fcrew that 

 clofed up its end (which was \ an inch long, and a little more than -}-^x\\ of an inch in dii- 

 meterj was prefled down againft its leather collar with the utmoft force. The manner of 

 fetting fire to the charge was as follows : A block of wrought iron, about if inch fquare, 

 with a hole in it capable of receiving nearly the whole of that part of the fhort tube which 

 proje£ls beyond the barrel, being heated red hot, the end of the fliort tube was introduced 

 into this hole, where it was fuffered to remain till the heat, having penetrated the tube, fet 

 fire to the powder it contained, and the inflammation was from thence communicated to the 

 powder in the chamber. 



The refult of this experiment fully anfwered the expeflation of the author. The gene- 

 rated elaftic fluid was fo completely confined that no part could make its efcape. The report 

 of the explofion was fo very feeble as fcarcely to be heard. It certainly could not have been 

 heard at the diftance of 20 paces. It refembled the noife occafioned by breaking a very 

 fmall glafs tube. The quantity of powder made ufe of in this experiment was not more 

 than i-8th of what the chamber was capable of containing. 



The next attempt was to meafure the force of the elaftic vapour thus confined. A hole 

 was bored in the axis of one of the fcrews, or breech pins, which clofed up the end of the 

 barrel juft defcribed, and aplfton of hardened fteel was fitted into this hole, which was I'jths 

 of an inch in diameter. The end of the pifton, which proje£led beyond the end of the 

 barrel, was then caufed to a£t upon a heavy weight, fufpended as a pendulum to a long iron 

 rod. It was hoped that a dedu£lion of the preflure of the elaftic vapour might be made 

 from the length of the arc defcribed by this pendulum ; but the experiment was not found 

 to »nfwer, though various alterations and unprovement$ were made in the apparatus before 



the 



