JAM-POT BOMBS. In the early stages of the war it was found necessary to make bombs on the spot. The material used was generally a jam tin filled with shrapnel bullets, scrap iron, powdered glass and grass, etc. This was exploded by 2 one-ounce primers, two ounces gelignite, blastene or ammonal, and detonated by a No. 6 or 7 detonator, to which was attached a five-second fuse. The time could be regulated by length of fuse. MECHANICAL BOMBS. _Hand Grenade No. 5_, known as _Mills’ Hand Grenade_. Mills’ Hand Grenade No. 5 weighs about one and one-half pounds and is in constant and steady use at the front, being the best known of all grenades. It consists of an oval cast iron case, containing explosives and serrated to provide numerous missiles on detonation. In the center is a spring striking pin, kept back by a lever or handle, which, in its turn, is held in position by a safety pin. [Illustration: _HAND GRENADE NO. 5 (MILLS)._] Detonators and percussion caps connected by a short length of fuse are supplied with these bombs. When the bomb is to be used the bottom is unscrewed and the combined detonator and percussion cap is inserted in the space provided for it, the percussion cap being placed in the boring under the striking pin. When this is done the bottom is screwed on again as tightly as possible, using the special spanner provided for this in each box. Before throwing, the safety pin is removed and the bomb held with the lever in the palm of the hand. When the bomb is actually thrown the lever or handle is released; this releases the spring, which forces striker down on to the percussion cap, ignites fuse, sets off detonator and explodes bomb. GAS WARFARE The use of poisonous and asphyxiating gases, which was first adopted by the Germans in the Ypres salient in April of 1915, is now becoming an accepted fact in the present war. It is to a certain extent in one shape or another, before one every day of his life in or near the trenches. Every one should therefore be well acquainted with the various ways in which gases are used in an attack, as well as precautionary methods to be taken in counteracting its effects while on the defense.