The scientific world is deeply indebted to General Jacob, of the Scinde Horse, for the zeal and energy he has displayed in carrying out his principle of projectiles. He experimented on a scale never before attempted by any private individual; his explosive projectiles have created universal interest, and the great ranges he obtained will hand down the General’s name in the history of gunnery to all future generations. Whilst ascribing all credit to General Jacob for the benefit he has bestowed on projectile science, it is not less my duty to point out how unfortunate for science, and for the General’s scientific reputation, were the defects which exist in the system of which he is so strenuous an advocate. General Jacob’s principle differs from mine as widely as the poles are separated from each other. In mine there exists the least amount of friction, the minimum of spiral motion, and a most extensive range, with the smallest expenditure of expellant force. In the General’s invention these points are exactly reversed: friction is at the highest point, the degree of spiral in the groove is more than double, and the charge, as a matter of course, is much greater. The range is greater, no doubt; as it ought to be, being obtained at treble cost. Cost, in all cases, is the key to success or failure; not cost in a monetary sense only, but cost of wear and tear. Destruction of the barrel, and the amount of buffeting by recoil, are points of cost; and the principle of General Jacob is so nearly allied to that of the “hexagonal” rifle, that many will think, and perhaps not without good reason, that the one has given rise to the production of the other. The great length of column, 2-1/2 diameters in height, is so extreme, as to be evidence in itself of the very unsound principles on which this rifle is constructed. When bullets composed entirely of lead are used, the result is that the bullet is so driven in upon itself, as to upset the whole structure, “swaging” it whilst in the barrel into a long cylindrical tube of lead, as the wood-cut, exhibiting the bullet before and after firing, will sufficiently explain; whilst the friction and lateral pressure on the tube of the barrel, which must be necessary to effect the change in the bullet, require no further comment. [Illustration: POINT OF BULLET BEFORE FIRING.] [Illustration: WHOLE BULLET AFTER FIRING.] The experience gained by General Jacob induced him subsequently to adopt an iron or zinc-pointed bullet, as is depicted in the wood engraving. [Illustration: COMPLETE BULLET.] [Illustration: METAL POINT.]