150

NEW EXPERIMENTS

TRACT 34,

of much less strength; and on trying the rest of the bar-rels, they were found to be all the same with this secondone: so that the first barrel of this year, had been a sin-gle one, of a greater strength, that had accidentally beenplaced with the rest. As we had made a considerable pro-gress in the experiments, it was material to find a powderof precisely the same strength with that we had last beenusing. But, as this was not to be found among these bar-rels, in their present state, we had recourse to the expedientof sifting some of the large grains out of the general mass,and, repeating the operation, we found the remainders gra-dually increase in strength, till at length the eprouvetteshowed the small grains to have the same strength, viz, be-tween 42 and 43, as the former kind ; a practice which wecontinued ever after. And thus the eprouvette not only de-tected a mistake, which would otherwise have spoiled thewhole year’s experiments, but :.lso enabled us to discover amethod of preparing a kind of artificial powder, to matchthe former.

195. The chief object of the experiments was, again fur-ther to ascertain the resistance of the air, by dischargingthese larger balls, as formerly the smaller ones, againstthe pendulum from different distances, and observing howmuch velocity was lost by flying through several spacesof air. Though several other objects were also proposed,and attended to, in the progress of the experiments; suchas, the effects of either suspending the guns like a pendu-lum, or stopping their recoil ; also the effect of differentweights and lengths of guns ; and the effect of the differentcharges of powder. The penetrations of the balls, in theblocks of elm wood, it was also proposed to attend to: butthese turned out so deep, that a piercer could not be foundlong enough to reach the ball within the block, though itwas sometimes introduced as much as 2G inches ; so that theball must have penetrated upwards of 29-E inches, in the so-lid wood, as the ball’s diameter was more than 3 inches anda half.