Page:Popular Science Monthly Volume 91.djvu/861

 Popular Science Monthly

��Ten tons of powder in 20-inch prisms propel the shot, which encounters an atmos- pheric resistance at the muzzle of 10.45 tons which fades off to zero at the first point of impact. Ignition is reversed ; the powder commences to burn at the shell's base and works back to the breech-plug so that the air is not filled with burning powder grains, as is usually the case. Fired point-blank the shell travels twenty- one miles parallel with the earth's curva- ture, which would permit the shot to perforate two German fleets side by side. At a 70-mile range the gun's possible de- structive area is 15,386 square miles; at the 100-mile range, 31,400 square miles.

If this gun were using its 70-mile range and it were located at Somerville, New Jersey, it would command New York City, Philadelphia, West Point, Mauch Chunk, Wilmington, Delaware and all the inter- vening country. One gun on the Panama Canal would command both entrances with deadly accuracy.

The power required to operate the gun is furnished by its own recoil. The rifle auto- matically assumes the position for firing.

The first part of the recoil is ab- sorbed by com- pressed air cylin- ders connected with a series of glycerine cylinders. At the end of the recoil the gun is locked in a horizontal position through compen- sating gear and is ready for automatic cleaning and load- ing, after which it automatically ele- vates itself and fires.

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��The gun is started and stopped by a foot press. The elevation is recorded by a left- hand wheel operating three dials — a degree dial, a second dial and a minute dial, while the point of compass is controlled by a right-hand wheel with three other dials geared for degrees, minutes and seconds. Since harbors can be ruled off into imagina- ry numbered squares, it is merely necessary to telegraph the office in charge of the gun that the hostile fleet is in square 22 or 64. The operator places a pantographic pointer on a metallic map at the position designated and the gun does the rest. The area of each square is coincident with the shell's own destructive area, while the whole metallic map is coincident with the gun's destruc- tive area.

The carriage weighs 98,492.5 tons with- out the gun. It is practically an automo- bile car resting on 250 soft iron wheels, each of which is 2 feet wide and 2 feet in diameter with 12 grooves in the rims for the rope tires.

Each wheel's bearings are a fork, like an inverted "U," the handle being a plunger terminating in a compressed-air cylinder. All cylinders are connected and sub- ject to the same pneumatic balance. Each wheel may be turned in any direction by a gear which connects all wheels. Power is transmitted to a certain number through double cranks in a double

��If the largest cask you ever saw were placed in the mouth of the gun it would probably look as tiny as the one shown here at the left

���In the drawing above you get a fair idea of the length of the bore of the new gun. It could accommodate an engine and a train of three usual-size cars

���An idea of the size of the shell used is given at left. An ordinary eight-cylinder automo- bile could be carried in it and there would be plenty of room to spare

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