Each battalion has with it two machine guns, manned by an officer, a sergeant, and sixteen men. Two wagons accompany this section to convey the guns and their ammunition. A machine gun is nothing but a rifle barrel fixed into a machine so that it becomes self-firing. The barrel is surrounded by a large tube filled with water, to keep the barrel from getting too hot. The gun is so fixed on a tripod stand that it can be turned round in any direction. One man carries the gun, which weighs about sixty pounds, to the selected position, and the other carries the tripod on which it is fixed. On the march, both gun and tripod are carried in a wagon. Each gun is supplied with boxes containing 3,500 rounds, and 8,000 more rounds are kept in reserve. On the next page you will see a picture of this gun at work. When it is fixed and sighted, a button is pressed, and the first shot is fired. The recoil of this shot empties and reloads the gun, and so the process goes on just as long as the button is pressed. Some three hundred shots can be fired in a minute very accurately, and the effect on a body of men advancing along a road or across a bridge is deadly in the extreme. [Illustration: A concealed machine gun in action. _Photo, Newspaper Illustrations Ltd._] Besides their rifles and bayonets, each infantryman carries a light, short-handled shovel attached to his belt. This is for making trenches and rifle pits to afford protection against the enemy's bullets. In a very short time a battalion can "dig itself in," and, thus protected, fire on the enemy from shelter. A trench a hundred yards long, three feet deep, and two feet wide, can be dug in easy soil by forty men in about three hours. Every battalion is accompanied by mules or carts, carrying picks and additional shovels. [Illustration: A trench made by infantry. In the drawing the trench has been cut through vertically to show how it is made. "a" is the parapet piled up behind the hedge to protect the firer, who is shooting through a loophole ("d") made of bags of earth. "b" is the bank of earth thrown up behind the trench to protect the men from the "back blast" of shells, for when they burst, their effect is felt as severely behind them as in front. "c" is the bank of earth at the end of the trench to protect the men from enfilade fire--that is, from fire along the length of the trench. Frequently trenches are made in zigzags to avoid this danger.]