Mr. ROBINS, for determining the initial velocity of shot, arising from different quantities of powder, made use of balls of about an ounce weight; whereas Mr. HUTTON, for the same purpose, hath employed those of different weights, from one pound to nearly three; or, in other words, Mr. ROBINS made trial with musket-shot only, Mr. HUTTON with cannon-balls from 20 to about 50 times heavier. This was a considerable step gained in a disquisition of that part of the science, in which the resistance of the air and other circumstances were not concerned; and where neither analogy alone, nor mathematical deductions alone, nor the two combined, were sufficient for establishing principles applicable to the motion of cannon-balls, without making a new series of experiments: and with what labour and judgment these have been performed, you understood by the account which Mr. HUTTON gave of them in his Paper. But should it now be inquired, what advantages may be derived from Mr. HUTTON’s experiments, for the advancement of the art of gunnery, and of philosophy in general? I would reply, that as to the former it may be sufficient to observe, that though the improvements be only such as can be deduced from the force of fired gun-powder; yet they are in a higher, more certain, and in a more general manner, than what resulted from the labours of Mr. ROBINS; who indeed led the way, but who made, as it were in miniature, those experiments which Mr. HUTTON hath executed at large, and which ROBINS himself wished to have made, as well as others who have considered the subject since his time. Now these experiments, though made by Mr. HUTTON with cannon-balls of a small size, may nevertheless form just conclusions when applied to cannon-shot of the largest size. And such conclusions inform us of the real force of powder when fired, either in a cannon or a mortar, impelling a ball or bomb of a given weight; that is, they discover with what velocity a given quantity of powder drives those projectiles in a second, or in any other assigned portion of time. They also shew the law of variation in the velocity arising from different quantities of powder, with the same weight of metal, and likewise that law which takes place upon using balls of different weights. Further, they point out the advantage obtained by diminishing the windage in cannon, and teach us how we may increase the weight of the shot in the same piece, by making it of a cylindrical form, instead of a spherical: by this device, a smaller ship may be enabled to do the execution of a larger one. And experiments of the same kind will also determine the just length of cannon for shooting farthest with the same charge of powder.