Page:Popular Science Monthly Volume 91.djvu/54

 Our Big Guns and How They Are Made

It is the most powerful thing on earth, is a great gun, but its actual firing life is not as long as the life of a butterfly

Illustrations by Kadel and Herbert

��IT is not easy to understand what the power of a gun really is — its penetrat- ing and destructive power. What we call a 15-inch gun — which means one whose muzzle or hollow part is 15 inches in diam- eter — will hurl a shell right through a plate or wall of the hardest steel 12 inches thick seven miles from the muzzle. The power of the very largest land guns ever made — the German howitzers or 16.5-inch guns — is such that one of their missiles cracks open a steel and concrete fort as if it were a nut.

"Built-up" and Wire- wound Guns and What They Are There are two classes of guns — naval guns and army or land guns. Because they can be manipulated more easily than those of a ship, land guns are the heavier. From eight to ten miles is the greatest distance that a gunner can cover success- fully at sea. The largest naval gun is the 15-inch English gun on the famous super- dreadnought, and the largest land gun is the German howitzer. Of the two the naval gun fires a shell weighing over half a ton, while the other fires a projectile a ton in weight. But the new giant 16-inch

��guns of the United States defending the Panama Canal and New York at Sandy Hook shoot projectiles weighing 2,370 pounds, which is over a ton. These im- mense steel guns can sink a ship before it has really come into sight on the horizon, the location of the battleship having been determined by airplane or tower.

How are these huge pieces made? The first step is the making of the pig iron from iron ore in large furnaces like towers, called blast furnaces. Then the pig iron is melted with other steel in large steel furnaces called "open hearth," until it is freed of its impurities and converted into steel. -

The melted steel, thin as water, is run from these furnaces into big iron molds where it is allowed to cool into large solid cylindrical or corrugated blocks. After cooling these are reheated and reduced in size by pounding them with big steam ham- mers and squeezing them in rolls until at last the steel is pressed into a long barrel- like mass, the embryo of a real gun. This long skeleton of the inside of a gun must be bored out from one end to the other on immense lathes, some over

���The man is leaning against his completed work — an immense steel gun — the most powerful product of his skill. The various hoops that go to make up such a weapon are easily picked out — large steel bands which are put on one after another as described in the article. It is impossible to determine whether this is a built-up or wire-wound gun. The breech is clearly shown

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