Page:Popular Science Monthly Volume 92.djvu/715

 The Mechanical David

Centrifugal force propels the bullets towards the enemy with terrific force, at the rate of 20,000 a minute

��THE present world war has brought out so many striking reversions to primitive principles and methods of attack and defense that the invention of a gun based upon the same principle that enabled David to lay low the mighty Goli- ath, should, by rights, cause no particular surprise. The gun, which is shown in the accompanying illustra- tion, is the invention of Levi W. Lombard of Boston, Mass. Its

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��general appear- ance is more that of a feed cutter or coffee- mill, but it is said to be cap- able of firing 20,000 projec- tiles a minute with sufficient force to penetrate steel plates three quarters of an inch thick at a distance of several

���hundred feet, a noteworthy achievement. The Lombard gun is based upon the principle of centrifugal force. A disk, twelve inches in diameter, which is rotated at the rate of 20,000 revolutions a mmute, has a curved ridge from its center to op- posite points of its periphery. The ridge has a groove on one side, which forms the channel for the bul- lets. These are fed from the center of the disk, one at every

��o «4Di5K9vn Looking down into the hop- per from which the bullets are fed to the rapid-fire gun

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The disk of the gun may be revolved by an elec- tric motor, a gasoline engine or by hand power

��revolution and are expelled by the centrif- ugal force of the revolving disk. The bullets leave the gun all in the same plane, but not all in the same direction. They come through a slit in the casing of the re- volving disk, which represents about five degrees of the per- iphery. Actual tests have shown that the linear velocity of the bullets (2000 feet per second) is greater than the velocity of the disk.

It is stated that, no matter what may be the speed of the disk, the bullets always come out at the same place. This result, which involves compli- cated mathematical and me- chanical problems, is obtained by the feeding mechanism and the peculiar form of the curve of the grooved ridge. One of the illustrations shows a top view of the feeding hopper. The gun may be revolved by an electric motor, a gasoline engine or by hand power.

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