Kelly Miller's History of the World War for Human Rights

by Kelly Miller

The tanks which were introduced by the English, move along on revolving platforms, so to speak. These platforms enable the tank to overcome all obstacles as the caterpillar tread is curved up in the arc of a huge circle at the front which gives the vehicle its wonderful tractive powers. This large curvature acts as a huge wheel with a tremendously long leverage equal to the radius of the circlet or the spokes of the imaginary wheel of the same diameter. Only that portion of the assumed wheel which would come in contact with the ground acts as the lever, and it is just this portion that is reproduced in the front end of a caterpillar belt.

Although varying in size and details, all tanks have the common characteristic of being divided into three main compartments between the two side caterpillar frames. The first is the observation compartment in which the driver and his helper are perched high above the ground to direct the movements of the huge steel beast.

In the middle is the ammunition room from which the guns carried in the two side turrets are fed. At the rear is the engine room. From two or four gasoline engines are used—these driving the rear axle and its integral sprockets over which the caterpillars run. The latter run an idler pulley or sprockets at the extreme front ends and are supported by means of rollers attached to the upper portion of the frame on each side when passing over the top. This movement of the caterpillar belts is exactly analogous to that of the ordinary variety of garden insect with the same name which similarly lays down his own track by humping his back continuously and regardless of the land surface.

The tanks are steered by a pair of small ordinary wheels at the rear. These are supported in a pivot on a frame extended from the rear. They are merely for steering, and support none of the weight of the tank except when bridging wide trenches or dips in the surface. Steering can be accomplished by making one caterpillar go faster than the other by manipulating clutches on the driving mechanism.

TANK'S "CATERPILLAR" FEATURE.

The "caterpillar" feature of the tank had its origin in the caterpillar belts or shoes which were first used on the great field guns and mortars—those tremendous weapons which shoot bombs and shells weighing tons and containing 500 or more pounds of guncotton or explosive which on contact is discharged, rending everything for yards around.

These guns, as well as the smaller field guns, have had attached to them great shields of steel behind which the gunners stand, so that they are protected against the old-fashioned sharpshooters whose duty it was to pick off the gunners.

The caterpillar or wheel belts on the big guns consist of flat blocks, or shoes, wider than the tires of the wheels. They are hinged and fastened together so as to form a great chain, and when placed on the wheels present broad surfaces to the ground and keep the gun carriages from sinking into the soft earth. With a set of these shoes a heavy gun can be drawn over soft and irregular ground, which would be almost impassable where the gun is mounted on wheels of ordinary width.

Before these belts were devised it was necessary for every gun crew to carry a supply of beams, jackscrews and devices to be used in extricating the heavy guns when they got fast in the mud. Now every gun has these belts which can be put on or detached in a few minutes.

Paradoxically, this is the day of the big gun's greatest effectiveness, and the day of its greatest limitations. The war has taught us more in two years about gunnery and the effect of various types of ordnance under varying conditions than could have been learned in twenty years of theoretical research—for actual experience proves where theoretical research merely gives ground on which to base an opinion.