-TRACT 34,
Gunnery experiments.
C5
113. The foregoing tables contain the several mediumsof velocities, for each clay, and for all varieties in the ciricumstances of powder, and weight and diameter ot ball. Itwill now then be proper to collect together all the repeti-tions of the same charge or weight of powdef, and to takethe mediums of all those mediums, to serve a s fixfed radi-cal numbers, or established degrees of Velocity, adapted toall the various charges of powdef, arid lefigth Of gtiil. Now,for this purpose, it may be proper to reduce the numbersof these tables all to one common weight and diameter ofball, namelyy to the weight 16 cJz 13 dr* and the diameter1*96 inches, which are the numbers that most commonlyoccur. And this reduction will be very well deduced fromthe experiments Of September 11, 1T84; when severaltrials were made with divers weights and diameters of ball,and with both 4 oz and 8 oz of powder, the results of whichaccord very well together. In the experiments of that day,it was found that, with the 4 oz charges, \ of the wholeVelocity is lost by the difference of ^ of an inch in thediameter of the ball; and, with the 8 oz charge, T * r of thevelocity is lost by the same difference ot windage. But thequantity of inflamed fluid which escapes, will he nearly asthe difference between the area of the circle of the bore andthe great circle of the ball, or the force will be as the squareof the ball’s diameter ; and the velocity 7 , we know, is as thesquare root of the force: therefore the velocity is as thediameter of the ball ; and the difference in fhfe velocity, asthe difference in the diameter, or as the wifidage. Hence,if w denote any difference of windage in parfs of an inch,or difference between l - 96 and the diameter of afty ball,and the part of the experimented velocity lost by T V of
an inch difference of windage; then shall : w :: ~which last term will show what part of the experimented ve-locity is lost by tlie increase of windage denoted- by 10.By this rule then, I reduce all the velocities to what they 7would have been, had the diameter of the ball beeu CCm-
VOI.,. lit,
p