"How on earth can it do that?" asked the boy. "You can't squeeze a 16-inch shell down a 2.1-inch muzzle!"
"That's what the stick is for," came the reply. "The shell is round, like one of the old-fashioned cannon-balls you see piled up in village squares beside antiquated cannon. It weighs 200 pounds and has a bursting charge of 86 pounds of tri-nitro-toluol. The shell is bored to the center. You shove one end of the iron rod into the gun so that it sticks out about eight inches beyond the muzzle. Then you put the shell on the rod by the hole bored to the center. It looks like a toy balloon at the end of a child's toy cannon. Then you fire it, the iron rod is shot out, driving the bomb ahead of it and off she goes."
"Will it go far?"
"Far enough," the veteran said. "At an angle of projection of 45 degrees with the low muzzle velocity of 200 feet per second, the range of the bomb is 1244 feet and it takes eight seconds to come. That's the only good thing about it, sometimes you can hear it coming soon enough to dodge into a dug-out. But neither Minnenwerfers, nor the 5.6-inch nor even the 8.4-inch howitzers will win a trench. It takes mines to do that.
"So, in order to gain an advantage, one side or the other burrows deep tunnels in the earth, sometimes 16 feet down, sometimes 60, all depending on the soil and the plan. The men work underground like moles and they drive a long subterranean gallery until they come right below an important point, maybe an officers' dug-out or a grenade depot. Then they burrow upwards a bit, and put in a tremendous charge of explosive, melinite or something like that, and fix an electric wire. The earth is then rammed back into the gallery, an electric contact is made and whiz! bang! about forty tons of mixed heads, legs, bits of bomb-proof and earth go flying into the air, leaving a hole big enough to build a bungalow in and never see the roof.
"Then it's our turn. While the section of the Boche line is in confusion we dash across, while our artillery, behind us, smothers the rest of the line. We settle in the big hole and build our trenches from it and we've gained a hundred yards and can pepper the Boche trenches from their rear. A mine's a great thing, although, sometimes, it costs more men to consolidate and hold a place like that than to take it. The British have beaten us all at that game. They've got small armies of Welsh miners, doing nothing but that all day and all night long. They're used to it, it's their trade and they don't mind.
"Now, a listening patrol, which is what I began to tell you about, is a patrol generally consisting of four men, under an officer, which creeps out on No Man's Land during the night. By approaching near the enemy trenches, listening with their ears to the ground, the men can hear if there is any one at work under them. The earth—as you ought to know, being a telephonist—is a good conductor of sound, and if there's any tricky business going on, a listening patrol can find it out."
"What good does it do to know that some one is driving a mine under you? Do you desert the trench, then, until they blow it up?"
The veteran almost growled.
"Does a Frenchman desert a trench!" he said. "No, we find out exactly where they're digging, and start a tunnel from our side, right below the other. Then, when they're working busily, a little explosion below them smashes their tunnel into soup and they're all dead—and buried—without troubling any one."