1 1 2 Experiments to determine 



tion of ammunition, I made a great number of interest- 

 ing experiments with these guns, and also with the ship 

 guns on board the ships of war in which I made my 

 passage to and from America. 



It would take up too much time, and draw out this 

 paper to too great a length, to give an account in detail 

 of all these experiments, and of the various observa- 

 tions I have had opportunities of making from time to 

 time, relative to this subject. I shall, therefore, only 

 observe, at present, that the result of all my inquiries 

 tended to confirm me more and more in the opinion, 

 that the theory generally adopted relative to the ex- 

 plosion of gunpowder was extremely erroneous, and 

 that its force is in fact much greater than is generally 

 imagined. That the position of Mr. Robins, which 

 supposes the inflammation and combustion of gun- 

 powder to be so instantaneous "that the whole of the 

 charge of a piece of ordnance is actually inflamed and 

 converted into an elastic vapour before the bullet is 

 sensibly moved from its place," is very far from being 

 true ; and that the ratio of the elasticity of the generated 

 fluid to its density, or to the space it occupies as it 

 expands, is very different from that assumed by Mr. 

 Robins. 



The rules laid down by Mr. Robins for computing 

 the velocities of bullets from their weight, the known 

 dimensions of the gun, and the quantities of powder 

 made use of for the charge, may, and certainly do, very 

 often give the velocities very .near the truth ; but this is 

 no proof that the principles upon which these computa- 

 tions are made are just ; for it may easily happen that 

 a complication of erroneous suppositions may be so 

 balanced that the result of a calculation founded on 



