33$

NEW EXPERIMENTS

TRACT 34.

be about three times as great as that above, computed from thenature of perfect and infinitely compressed fluids, as Mr. Ro-bins thinks he has found it to be, then shall the velocity atthe gun lose its 28th part, and the greater velocity will beto the less, as 28 to 27. This however is a circumstance tobe discovered from our experiments, the result from whichwe shall hereafter have an opportunity of comparing withthe conclusion in this article, when it may either be confirmedor corrected.

On the Velocity of the Ball, as found, from the Recoil of the

Gun.

34. It has been said, by more than one writer on thissubject, that the effect of the inflamed power on the recoilof the gun, is the same, whether it be charged with a ball, orfired by itself alone ; that is, that the excess of the recoilwhen charged with a ball, over the recoil when fired with-out a ball, is exactly that which is due to the motion andresistance of the ball. And this it is said they have foundfront repeated experiments. Now supposing those experi-ments to be accurate, and the deductions from them justlydrawn ; yet as they have been made only with small balls,and small charges of powder, it may still be doubted whetherthe same law will hold good when applied to such cannonballs, and large charges of powder, as those used in ourpresent experiments. Which is a circumstance that remainsto be determined from the results of them. And this deter-mination will be easily made, by comparing the velocity ofthe ball as computed from this law, with that which is com-puted from the vibration of the ballistic pendulum. For ifthe law hold good in such cases as these, then the velocityof the ball, as deduced from the vibration of the gun, willexceed that which is deduced from the vibration of the pen-dulum, by as much as the velocity is diminished by the resist-ance of the air between th* gun and the pendulum.