Courtesy of the Bethlehem Steel Co.

Military cannon are divided into three classes, based upon the length of caliber, and technically known as guns, mortars and howitzers. In guns the length is relatively great, in mortars relatively small, compared to their calibers. Howitzers form a class between guns and mortars in length. The field guns of the American army are the 3.6-inch breech-loading mortars, and the 3.6-inch heavy and 3.2-inch light guns. The siege guns in the service are the 5-inch siege guns, the 7-inch howitzer, and the 7-inch mortar. The coast defense artillery consists of the 8-, 10-, 12- and 16-inch guns and the 12-inch mortars. In the recent European war very heavy cannon were used for field service, pieces of the size usually placed in forts being drawn to the field by powerful tractors, set on concrete platforms and used in attacks on fortified cities. It was through the use of such ordnance that the German army so easily reduced the strongly fortified Belgian cities.

Fluid Compression Plant.

While still in a molten condition in the mold, the steel used in manufacturing guns and shafting is subjected to hydraulic pressure until the ingot has cooled, thus insuring the solidity of the metal. The upper head of the compressor weighs 125 tons, and the lower one, including the cylinder through which the hydraulic pressure is applied 135 tons.

Courtesy of the Bethlehem Steel Co.

The range of these giant cannon is enormous and their destructive power great this being added to by the fact that the explosive shell has replaced the solid round shot of old-time gunnery. A 14-inch gun of 45 caliber can discharge a 1,400-pound projectile at a muzzle velocity of 2,600 feet per second. If we compare this with a locomotive going at the speed of sixty miles an hour, we have in the latter a speed of eighty-eight feet per second to compare with the 2,600 feet per second of the cannon ball. From this we can well conjecture the vast speed with which the latter moves, its enormous range and vast powers of destruction.

Ammunition.* (See page 410.).

Two-Handed Elevating Gear.* (See page 410.).

* Illustrations by courtesy of the Bethlehem Steel Co.

Range Finder and Predictor; Home and Distant Station Instruments.*.

(See page 410.)

Armor Piercing Projectiles, Capped and Uncapped.* (See page 410.).

* Illustrations by courtesy of the Bethlehem Steel Co.

Range Finder and Chart Attachment*. (See page 410.).

Eighteen-inch, Thirty-caliber Torpedo Gun.* (See page 410).

* Illustrations by courtesy of the Bethlehem Steel Co.

Firing Gear for Guns.* (See page 410.).

Fuses.* (See page 410.).

* illustrations by courtesy of the Bethlehem Steel Co.

As facts are better than theories, it will be of interest to adduce a recent example of gunnery of a most illuminating type, but as regards distance and remarkable accnroov of aim. In September, 1916, the American battleship "Pennsylvania," armed with a main battery of twelve 14-inch guns, fired these simultaneously at a target in the Chesapeake 22,000 yards, or more than twelve miles, away. The target was the sunken hulk of the "San Marcos," formerly the battleship "Texas," which for several years had been used for similar purposes. As the target was invisible to the gunners it was hardly to be expected that any of the shots should fall near the target. But the extraordinary result appeared that five of these twelve shots struck the hulk. As each of these projectiles weighed 1,400 pounds any battleship receiving such a broadside would probably have gone promptly to the bottom. The result, which has never before been equaled in accuracy, sufficiently attests the remarkable proficiency in range-finding that modern engineers have developed.

Three-inch Horse Artillery Gun, Long Recoil Carriage and limber.

Length of gun, 85 inches (28 calibers). Weight of projectile, 12 pounds. Travel of projectile in bore, 74.65 inches (24.88 calibers). Weight of charge, 17.1 ounces of smokeless powder. Muzzle velocity, 1,750-foot seconds. Muzzle energy, 255-foot tons. Weight of gun, carriage and limber, containing 36 rounds of ammunition, 3,355 pounds. Ground clearance, 18 inches.

Courtesy of the Bethlehem Steel Co.

As for the penetrating powers of such huge shot we may take the 15-inch gun, the type of the largest guns in our fortifications and which is claimed to be able to pierce sixteen inches of armor at a range of 18,000 yards and ten inches at a range of 20,000 yards. A notable example of this took place on September 15, 1916, at the proving grounds at Indian Head, on the Potomac River, when a 16-inch, 2,100-pound, solid steel shell, said to be the first ever fired from a naval gun of that caliber, with a small charge of explosive, went through a plate of armor, penetrated a thick sand backing, and continued its course, striking the house of an employee of the proving grounds and plunging through the kitchen rending all before it. This was a naval gun, the largest yet made for naval purposes.

Patented Chain Rammer.

As applied to loading twelve-inch turret guns. The space occupied by this rammer in the rear of the gun is less than one foot, with a possible ramming stroke of fifteen feet. The rammer being attached to the gun's cradle or slide, moves with the gun in elevation and depression. The ammunition car also moves with the gun. Loading can be performed while the gun is kept in motion following a moving target. This rammer is stiff in all directions when extended.

Courtesy of the Bethlehem Steel Co.

In the make-up of modern guns the breech-loading mechanism is of essential importance, it being necessary that the breech should be capable of rapid opening for the insertion of the charge into the loading chamber, as rapidly closed and firmly secured to prevent it being forced open by the reaction of the discharge. It also must fit with such tightness as to prevent any escape of the gas in that direction, and force it to exert all its impelling power upon the ball. Various methods are used for this purpose, with the result that loading and firing can be very quickly and effectively performed. In the case of guns in fortifications, the disappearing carriage is a highly important invention of recent date. By its aid the gun is quickly lifted to fire over the walls of the fort and is driven backward by the force of its discharge, sinking to a place of safety behind the walls. This saves the gun and its crew, from injury by return fire.

We may say in conclusion that the great European war was notable for the use of artillery to an extent far surpassing its employment in any previous war. This great conflict, indeed, was very largely a contest of gun fire, in which the opposing fields of the battling armies were so swept with shells and other explosives as to render life impossible on the open land, trench digging being one of the main employments of the embattled hosts. Never before had the supreme value of gunnery in warfare been so fully demonstrated.

Gear Wheel and Drum for Coal Hoisting Plane.

Diameter of wheel, 20 feet 9 1/2 inches; face, 43 1/2 inches; diameter of hub, 26 inches; number of teeth, 128; pitch, 6 1/8 inches; pitch diameter, 249.554 inches; shipping weight, 108,873 pounds.

Courtesy of the Bethlehem Steel Co.

Six-Inch Ribbed Cavity Armor-Piercing Shell.

Projectile was loaded with two pounds of black charcoal powder and fused with magazine fuse. Fired at six-inch Krupp hard-faced armor plate. Shell burst about eight feet to rear of plate after penetrating the same. Weight of largest fragment recovered 10 1/4 pounds. Average weight of fragments, 2 5/26 ounces. Total number of pieces recovered, 650.

Courtesy of the Bethlehem Steel Co