234 Count Rumford’s Experiments to determine 
above the boiling point, can easily perceive that its elasticity 
must be almost infinite when greatly condensed and heated to 
the temperature of red-hot iron; and this heat it must cer- 
tainly acquire in the explosion of gunpowder. But if the force 
of fired gunpowder arises prmcipally from the elastic force of 
heated aqueous vapour, a cannon is nothing more than a steam- 
engine upon a peculiar construction ; and upon determining 
the ratio of the elasticity of this vapour to its density, and to 
its temperature, a law will be found to obtain, very different 
from that assumed by Mr. Robins, in his Treatise on Gunnery. 
What this law really is, I do not pretend to have determined 
with that degree of precision which I wished ; but the experi- 
ments of which I am about to give an account will, I think, 
demonstrate in the most satisfactory manner, not only that the 
force of fired gunpowder is in fact much greater than has been 
imagined, but also that its force consists principally in the 
temporary action of a fluid not permanently elastic, and con- 
sequently that all the theories hitherto proposed for the eluci- 
dation of this subject, must be essentially erroneous. 
The first step towards acquiring knowledge is undoubtedly 
that which leads us to a discovery of the falsehood of received 
opinions. To a diligent inquirer every common operation, 
performed in the usual course of practice, is an experiment, 
from which he endeavours to discover some new fact, or to 
confirm the result of former inquiries. 
Having been engaged many years in the investigation of 
the force of gunpowder, I occasionally found many oppor- 
tunities of observing, under a variety of circumstances, the 
various effects produced by its explosion ; and as a long habit 
of meditating upon this subject rendered every thing relating 
