156 Expefiments to determine 



experiments, all made with charges of 12 grains of pow- 

 der, there were no less than 5 in which the weight was 

 raised with a report ; and as the same weight was moved 

 in 3 different experiments in which the charge consisted 

 of less than 12 grains, there does not appear to be any 

 reason whatever for doubt with regard to the principal 

 fact on which the above computation is founded. 



There is an objection, however, that may be made to 

 these decisions respecting the force of gunpowder, which 

 on the first view appears to be of considerable impor- 

 tance ; but on a more careful examination it will be 

 found to have no weight. 



If the force of fired gunpowder is so very great, how 

 does it happen that fire-arms, and artillery of all kinds, 

 which certainly are not calculated to withstand so enor- 

 mous a force, are not always burst when they are used ? 

 I might answer this question by another, by asking how 

 it happened that the barrel used in my experiments, and 

 which was more than 10 times stronger in proportion to 

 the size of its bore than ever a piece of ordnance was 

 formed, could be burst by the force of gunpowder, if its 

 force is not in fact much greater than it has ever been 

 supposed to be ? But it is not necessary to have re- 

 course to such a shift to get out of this difficulty ; there 

 is nothing more to do than to shew, which may easily 

 be done, that the combustion of gunpowder is less rapid 

 than it has hitherto been supposed to be, and the ob- 

 jection in question falls to the ground. 



Mr. Robins's theory supposes that all the powder of 

 which a charge consists is not only set on fire, but that 

 it is actually consumed and " converted into an elastic fluid 

 before the bullet is sensibly moved from its placed 1 have 

 already, in the former part of this paper, offered several 



