VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 143 



stand the amazing force of the inflamed gunpowder as the others. It was so much 

 and so irregularly corroded, by the explosion in the first experiment, as to be rendered 

 quite unserviceable; and the barrel itself, notwithstanding its amazing strength, 

 was blown out into the form of a cask; and though it was cracked, it was not 

 burst quite asunder, nor did it appear that any of the generated elastic fluid had 

 escaped through the crack.* 



These unsuccessful attempts, and many others of a similar nature, of which it 

 is not necessary to give a particular account, as they all tended to show that the 

 force of fired gunpowder is in fact much greater than has generally been imagined, 

 instead of discouraging me from pursuing these inquiries, served only to excite my 

 curiosity still more, and to stimulate me to further exertions. These researches did 

 not by any means appear to be merely speculative; on the contrary, I considered 

 the determination of the real force of the elastic fluid generated in the combustion 

 of gunpowder as a matter of great importance. The use of gunpowder is become 

 so extensive, that very important mechanical improvements can hardly fail to result 

 from any new discoveries relating to its force, and the law of its action. Most of 

 the computations that have hitherto been made relative to the action of gunpowder, 

 have been founded on the supposition that the elasticity of the generated fluid is as 

 its density;-}- but if this supposition should prove false, all those computations, 

 with all the practical rules founded on them, must necessarily be erroneous; and 

 the influence of these errors must be as extensive as the uses to which gunpowder 

 is applied. 



Having found by experience how difficult it is to confine the elastic vapour gene- 

 rated in the combustion of gunpowder, when the smallest opening is left by which 

 any part of it can escape, it occurred, that I might perhaps succeed better by 

 closing up the powder entirely, in such a manner as to leave no opening whatever, by 

 which it could communicate with the external air; and by setting the powder on 

 fire, by causing the heat employed for that purpose to pass through the solid sub- 

 stance of the iron barrel used for confining it. Inorder to make this experiment, I 

 caused a new barrel to be constructed for that purpose: its length was 3.45 inches, 

 and the diameter of its bore -fa of an inch ; its ends were closed up by two screws, 

 each 1 inch in length, which were firmly and immoveably fixed in their places by 

 solder; a vacuity being left between them in the barrel 1.45 inch in length, which 

 constituted the chamber of the piece ; and whose capacity was nearly -%-of a cubic inch. 

 A hole, 0.3 7 of an inch in diameter, being bored through both sides of the barrel, through 

 the centre of the chamber, and at right angles to its axis, 2 tubes of iron, 0.37 of an 

 inch in diameter, the diameter of whose bore was -jV of an inch, were firmly fixed 

 in this hole with solder, in such a manner that while their internal openings were ex- 

 actly opposite to each other, and on opposite sides of the chamber, the axes of their 



* This effect is to be explained also by the preceding note. + It might have been added, " when 

 of the same temperature," as Mr. Robins and others have proved it to be. 



