Specification forming part of Letters Patent No. 13,679, dated October 16, 1855.

To all whom it may concern:

Be it known that I, ANDREW HOTCHKISS, of Sharon, county of Litchfield, and State of Connecticut, have invented certain new and useful Improvements in Projectiles for Ordnance; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being made to the annexed drawings, making a part of this specification, in which -

Figure I is a side view or elevation, partly in section. Fig. II is a view of a part in detail.

Similar letters refer to similar parts throughout.

My invention is for certain improvements in projectiles for ordnance; and it consists in a method of constructing a cast-iron shot so that it shall be capable of being fired from rifled cannon, and also shall have effects similar to the slugging of balls in breech-loading guns. The shot is made in three distinct parts, two of said parts being of cast-iron or similar metal and the third of some softer and more flexible material - such, for instance, as lead - the whole, when combined together, forming, to external appearance, an egg-shaped shot.

The construction and operation is as follows: The body of the shot consists of a casting having one end formed into a blunted point, similar to the usual conical ball, as seen at A, Fig. I. The opposite end of this body from a little beyond the middle tapers off into a tail-piece, (seen at B,) and is also squared at the end. Upon each corner of the square the metal is cut away a little, so as to form a projection, (shown at the letter c,) the object of which will be explained farther on. About the middle of the body A two recesses are formed completely around, as at e and e', thus leaving a projection, I, between. Upon these the lead ring is cast, and the recesses and projection serve to keep it on. This ring is at C, part being shown in section. From the point at e' it will be seen that the inner surface is chamfered off, as shown, and leaves a cup-shaped termination.

The second casting will now be described. This consists of a cap which is to inclose the tail-piece B, and is to effect the expansion of the projecting edge of the lead ring into the grooves of the cannon. It is shown at E, Fig. I, with a view looking directly into the interior in Fig. II. The rim of this cap is chamfered or beveled off from the outside, as shown in the sectional part at I, and where it will be seen to fit in and press upon the like beveled ridge of the leaden ring. In the head of the cap inside is a projecting ring, s, through which four notches, s', are cut, as shown in Fig. II, and these permit the projections c to pass through. The object of this will now be made apparent, for by turning the cap slightly round the projections pass by the notches and become locked by the solid part of the ring, and thus the parts A and E are held together.

In order that the cap may expand the leaden ring, it must have play upon the tail B, for which, it will be seen, there is room left in the cavity t beyond. The tail acts also as a guide to the cap, insuring a direct forward motion, since without such guide the cap might be driven a little out of the true line, and the result would be that the ring, being more expanded on one side than on the other, would cause windage on that other side, and consequently destroy the accuracy of the fire.

The effects in the act of firing are as follows: The bore of the cannon must be spirally grooved on a principle similar to that of a rifle. The flat part of the ring C should fit the smooth part or "lands" of the bore. In sending it down the flexible ring may be slightly expanded by a blow of the rammer as soon as the shot is home. It is in the act of firing, however, that the ring C is expanded so as to take a full impression of the grooves, for by the force with which the cap E is driven toward the body of the shot, or A, and before momentum is communicated to the latter, the lead ring will be expanded, that being the point of least resistance, and be thereby caused to take the impression of the grooves, as also to be packed tightly against the rest of the chamber. This prevents windage, and of course insures the full effect of the powder, while at the same time rotary motion is imparted to the shot. The flexible ring also has this important advantage, that it does not wear or damage the grooves of the gun; even in case of "stripping," should such action occur, and hence there is no reason why the wear should not be as long as in the plain bore.

What I claim as of my invention is -

1. Constructing a shot or projectile capable of being fired from a cannon having rifle-grooves, said shot consisting of three parts, two of which parts are of hard metal and the other of some flexible expansible material in the form of a band or ring attached to one of the hard-metal parts and overlapping the edge of the other, in such manner that either by the act of loading or of firing, or of both, the said ring shall be so expanded or distended that it shall take the impression of the grooves and be made to fit the bore, as described.

2. The tail-piece for securing the cap to the body of the shot and as a guide to the cap in its forward motion, in the manner described.


Witnesses: S. H. MAYNARD,
                 WM. E. WHITE.