PREFACE. XIX

and deduces a number of inferences practicallyuseful and in general coinciding with the re-sults of experiments made in this country. Inthe second part, after expatiating upon the dif-ficulty of measuring the force of fired gun-powder, even when the utmost care and precau-tion are taken to guard against error and irregu-larity; and thence inferring the impracticabilityof doing it to an absolute certainty in militaryoperations, where a thousand circumstancesconcur to baffle the attempt: he asserts the ab-surdity of laying down any rule as regular andconstant; since the utmost that can.be obtainedis an approximation, sufficient with a tolerableshare of intelligence and accuracy for all com-mon purposes. To this end, he first considersthe force of powder in its most simple, and af-terwards in its most complex state: then havingdwelt on its modifications when fired in guns,he passes to an investigation of the initial velo-city of projectiles, of the law of their impulsion,and terminates the treatise with experimentson the resistance of the air. ,

Having m the former treatise, examined shenature and composition of gun-powder, andanalyzed it’s properties, the author in the secondwork, entitled a Treatise on Fire-arms, appliesthese principles to practice : but in order to

b 2 carry