The first of these fuzes is called Safety--and the outer covering is black. In this type the inner core burns quite slowly at the rate of two or three feet to the minute. This is the fuze which is used in the preparation of the jam-tin bomb: an instrument of destruction which has caused much amusement to the frivolous. A jam tin is taken and is filled with gun cotton, nails, and scraps of iron. Into the gun cotton is inserted a detonator; and into the detonator is inserted two inches of safety-fuze. The end of the safety-fuze is then lit, and the jam tin is presented to the Hun. It will readily be seen by those who are profound mathematicians, that if three feet of safety-fuze burn in a minute, two inches will burn in about three seconds--and three seconds is just long enough for the presentation ceremony. This in fact is the principal of all bombs both great and small. The second of these fuzes is called Instantaneous--and the outer covering is orange. In this type the inner core burns quite quickly, at the rate of some thirty yards to the second, or eighteen hundred times as fast as the first. Should, therefore, an unwary person place two inches of this second fuze in his jam tin by mistake, and light it, it will take exactly one-600th of a second before he gets to the motto. Which is "movement with a meaning quite its own." To Jim then came an idea. Why not with care and great cunning remove from the inner core of Instantaneous fuze its vulgar orange covering, and substitute instead a garb of sober black--and thus disguised present several bombs of great potency _unlighted_ to the Hun. The afternoon before they left for the reserve trenches he staged his comedy in one act and an epilogue. A shower of bombs was propelled in the direction of the opposing cave-dwellers to the accompaniment of loud cries, cat calls, and other strange noises. The true artist never exaggerates, and quite half the bombs had genuine safety-fuze in them and were lit before being thrown. The remainder were not lit, it is perhaps superfluous to add. The lazy peace of the afternoon was rudely shattered for the Huns. Quite a number of genuine bombs had exploded dangerously near their trench--while some had even taken effect in the trench. Then they perceived several unlit ones lying about--evidently propelled by nervous men who had got rid of them before lighting them properly. And there was much laughter in that German trench as they decided to give the epilogue by lighting them and throwing them back. Shortly after a series of explosions, followed by howls and groans, announced the carrying out of that decision. And once again the Hymn of Hate came faintly through the drowsy stillness....