Into this the instructor and his pupil sought refuge from the effects of the bomb explosion. As the explosion really is surprisingly violent and takes place at the longest only five seconds from the time the mechanism of the bomb is started, and at a maximum distance of thirty yards, the instructor and any one in the trench with him have got to be exceedingly spry in running under the bomb-proof in order to beat the bomb. There is, too, the danger of a premature explosion.
To make me feel more entirely at my ease, they told me that only a few days ago an officer of explosives brought a Colonel to see one of these demonstrations in another school, behind a different part of the line. As they came to the entrance of the trench the officer politely made way for the Colonel to enter the trench first. As the Colonel did so, the bomb exploded prematurely and killed the Colonel outright.
About twenty yards in front of the trench was dug a shallow dummy trench to represent a German target. Some 150 yards further distant was set up a section of wire entanglements.
We found the 128 soldiers ranged in line a few yards behind the trench. At its edge I took my place with the Captain of explosives and three or four other officers. The infantrymen lined up two deep behind us.
In the open recess in the trench stood the non-commissioned officer of engineers, facing backward toward us. He was the instructor. At the order of the Captain he placed an innocent-looking satchel on the trench edge at his right elbow, plunged a hand into it and briskly plucked out, one after the other, eight different varieties of bombs. Picking them up, one at a time, he gave a terse lecture on the construction and method of operation of each.
The bombs were all fully loaded, and the explosion of any one of them would have sent a great many of us well on the way to the cemetery. I noticed in some of the officers, and undoubtedly in myself, a certain tenseness as the engineer nonchalantly illustrated within an inch or two of actuality how a percussion bomb would explode if brought in contact with the ground.
In demonstrating the first grenade he adjusted around his wrist a loop with about eight inches of cord hanging from it. A heavy two-inch metal pin was attached to the end of the cord. Picking up a black spherical bomb slightly bigger than a baseball, he stuck the pin lightly into a hole in its side. The bomb was to be thrown with full force. In flying out of the hand it pulled itself free from the pin, causing a friction which ignited the five-second fuse. The pin of course remained behind, hanging to the cord, and was promptly stuck into another bomb. This bomb, being particularly heavy, could be thrown only fifteen metres by an average thrower and twenty as a maximum.
The second bomb was black and pear-shaped. It had a spring which looked like a nickel shoe-horn folded back tight against it. The pressure of the palm against the shoe-horn in throwing it released the spring and started the fuse, which, like all the rest, was set at five seconds.
The third bomb was a can of white tin attached by two wires to a white deal handle. A nail was stuck into a hole in the can. The nail was hammered in by a sharp rap against the ground. ("If you try to knock it in against the palm of your hand it would hurt," explained our instructor.) The nail, driven in, started the fuse.