28 THE PROPERTIES
vided that the two longest ranges of the two pieces, whencompared together, be unequal.
75. In seeking the charge that gives the longest range, itwill be found that by using small charges at first, and in-creasing the quantity of powder by degrees, the ranges willincrease to a certain point; after which, if the charge beaugmented, they will progressively diminish; though the re-coil will still continue in the ratio of the increase of thecharge. This is a consequence deducible from the fore-going experiments, and agreeable to the principles of me-chanics ; since the recoil and the range ought to be in thereciprocal ratio of the gun and the shot, making allow-ance for the resistance which these bodies meet with. Thus,when all the powder explodes, the recoil and the rangeought to be in the above ratio; but when a part onlytakes fire, the burning powder must not only impel thewad and the shot, but also the unfired grains. Now thesubstances impelled towards the muzzle of the gun being ingreater quantity, the weight approaches nearer to the weightof the gun, which always remains the fame, and the rangeis consequently diminished.
76. The following experiments will prove the third pro-perty of powder in fire-arms of all calibres. (70.) Let agun of any nature be taken, and, to simplify the experiment,be charged with such a quantity of powder as will all explode:on.examining the ranges from two equal charges of powder,of the fame quality, but of differently sized grains, as cannonand musquet powder, it will be constantly found, caterisparibus, that the range produced from the musquet powderis much longer than that from the cannon powder. Now asthe action of fired powder depends on the elastic fluid, theshot, in the longest range, must necessarily have been im-pelled by a greater quantity of this fluid: but it has been:demonstrated, (57.) that from equal charges of cannon andmusquet powder, equal quantities of the elastic fluid are ge-nerated when they are totally consumed; wherefore, in thiscafe, all the fluid is not generated in the time that the Ihot ismoving along the bore of the gun, and consequently we maycbnclude that its generation is progressive. A comparativetrial of all other kinds of powder that have the fame pro-portion in their ingredients, and differ only in the size ofthe grains, gives a similar result: whence it is clear, thateach grain is consumed progressively in pieces of all calibres;