Harper's Round Table, August 4, 1896

by Various

TESTING PROJECTILES ON ARMOR PLATE.

Still there are many things about projectiles that are common property, and we may talk about them freely. Every one must know that projectiles are made from hardened billets of steel, and that they are heated and rolled and pounded until they are of the desired shape and strength. Certain chemicals are put into them to give the steel additional strength, and the most careful adjustment, even to a one-thousandth part of an inch, is made when the projectiles are shaped finally. The test of the size and shape of these missiles is so thorough that the most delicate work is necessary in finishing them. You look at a 13-inch shell. It is probably three feet high, and weighs about 1100 pounds. It is anything but a delicate-looking object, and certainly the work it is intended to do is not delicate. A 13-inch shell, which is the largest size made in this country, is about as robust an affair as human skill has yet devised. To test such a shell two slender steel rings are used. One is two-thousandth part of an inch larger in diameter than the required size of the shell, and the other is two-thousandth part of an inch smaller. The larger ring must pass freely over the projectile, and the smaller ring must not pass over it. When one thinks of the difficulty of pounding or rolling a heated piece of ordinary steel into such a perfect shape, he can see what a delicate task it must be. But think how much more difficult it must be when certain alloys are put into the steel to make it so rough that it can be made to pass through a plate of hardened armor, say seventeen inches thick. Probably no more delicate mechanical work exists than in shaping these projectiles.

LOADING 13-INCH GUNS WITH 1100-POUND SHELLS AND POWDER CHARGES.

There are five places in this country where the projectiles for the cannons of the army and navy are made. Most of them use processes which are secured from Europe. The fewest possible number of persons, both in this country and abroad, know the secret of their production. The workmen in the factories do not know the various steps and compositions of the metals they use. Aside from the owners of the process and the chemists in their employ, almost no one else knows the secret. Each workman only knows his own part, and if they should all get together and each should tell what he knows, their combined knowledge would be of little value to them in discovering the secret. The chief places of manufacture in this country are at the Midvale Steel-Works, in Philadelphia, where the famous Holtzer projectiles are made; the Carpenter Works, at Reading, Pennsylvania, where the Carpenter projectiles are produced; the Wheeler-Sterling Mills, in Pittsburg, where the Sterling projectiles are made; the Johnson Works at Spuyten Duyvil, New York; and the United States Projectile Company's Works in Brooklyn. The three first named produce the larger projectiles used in our guns. At the Midvale Works, through which I had the pleasure of going by courtesy of the president, Mr. Harrah, before I wrote this article, one may see many picturesque things in the manufacture of steel, and it is possible that one may look upon some of the more rudimentary processes of projectile-making without knowing it; but when one comes to the place where the projectiles are really made, he finds himself facing a big fence with a locked gate, and a sign saying that no one, not even those employed in other work about the immense establishment, is permitted to go inside the barrier. A big bell hangs outside the gate, and if one wishes to speak with any one inside the enclosure, he must ring that and call out the man. There is a big open cistern outside, where the specially prepared water used inside the mill is collected, but that is all one can see. Inasmuch as all this secrecy is necessary to the welfare of our country, I am sure that the curiosity of all patriotic persons should stop at this point, and we must all go away satisfied and even pleased with all these precautions.

THE PARTS OF A SHELL.

Projectiles are of three kinds: the armor-piercing, the semi-armor-piercing, and the ordinary bursting projectiles, commonly called shrapnel. We are confining most of our efforts at present to making the armor-piercing and the semi-armor-piercing projectiles. The armor-piercing shot are practically solid pieces of metal. The semi-armor-piercing projectiles are hollow, and contain a bursting charge, usually of ordinary powder. The solid shot are for use in the large guns of ships, and are intended to pierce the armor of battle-ships and wreck their machinery. They simply break up the armor of a vessel. The semi-armor projectiles are for the same purpose, and also especially for use in mortar guns. These guns are short-muzzled affairs, and they throw their shells high in the air, so that they may come down on a deck, burst, and pass clear through a ship's bottom. The chief defences of New York harbor consist of a large battery of these mortar guns in the trees and behind the sand hummocks at Sandy Hook. It is estimated that only one out of two hundred shots that they fire into the air with a high curve will strike a war-ship attempting to pass into the harbor, but it is also known that one of these shots will pass through any ship from top to bottom, and, bursting as it passes through, will sink any vessel afloat. A 13-inch semi-armor-piercing projectile carries about fifty pounds of powder inside, and it is exploded by percussion—that is, by the shock of contact with a solid substance. The shrapnel shells contain bullets of various sizes, and they explode on percussion. Their object is to scatter bullets about a ship's deck and clear it of men, rather than to sink the ship.

A projectile is useless, provided it is of the solid kind, if it breaks in pieces when it hits its target. The energy of the gun and powder is all used up in breaking itself to pieces. If it passes through armor without injuring itself at all, the full energy of the gun is sent against the target, and the projectile does its complete work. A projectile is supposed to pass through armor one and one-eighth times its own diameter in thickness—that is, an 8-inch projectile is supposed to be a match for 9-inch armor, and so on.

There are five distinct parts to every projectile. They are the point, the ogival, the bourrelet, the body, and the base. The point, of course, is the extreme forward end; the ogival is the rounded part just behind the point; the bourrelet is a bright band of steel where the rounded part ends—it is intended to fit the bore of a gun closely, and with a tight grip; the body is the long, straight part; and the base is the flat end, with a band which grips the rifling of the gun, by means of which a revolving motion is given to the projectile as it is hurled against its target.