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470 trigger. In one case the source of power was an assemblage of coiled springs. In others, the rubber was replaced by a system of wire which, on being bent out of shape, stored up the power to reassert itself. In another, perhaps the last evolved during the war and certainly one of the most ingenious, centrifugal force was utilized, without previous storage of power.

Under the heading of bombthrowers as above defined should also come the class of pneumatic guns, certain representatives of which figured in the war on both sides, but owing to the general similarity of these to normal (i.e. explosive-propellant) trench ordnance they are treated along with the latter.

In naval usage, on the contrary, the term is applied to explosive-propellant derivatives of trench ordnance which were mounted on trawlers and other craft for the purpose of attacking submarines. The object was to throw for a certain distance very heavy charges of explosive that, equipped with a hydrostatic fuze, would act in the same way as depth charges. These bomb- throwers are dealt with under ORDNANCE: Naval Gunnery.

FIG. i.

The first form of catapult to become a regulation weapon in the British army in France was the " Leach," used in 1915-6. This was a strong forked wooden frame (fig. l) about 7 ft. in length from front to rear, the width at the splayed end or fork being about I ft. 10 in. Near the ends of the forked arms or " horns " were attached two sets of powerful rubbers, the rubbers of each set being firmly bound together at the extremities. The inner ends of these sets of rubbers were attached to the pouch or bomb receptacle of the catapult, which, when the rubbers were out of tension (and the pouch there- fore in its forward position), was about I ft. 9 in. from the front of the fork. When, in order to fire, the rubbers were pulled back to extreme tension the pouch was less than a foot from the tail end of the frame. This pulling back was effected by a wire attached to the rear of the pocket, which passed round a pulley on the tail to a gear-box on the underside of the frame. This gear-box contained a winding-handle, gear, and a retaining-pawl; when the handle was turned, the wire was drawn into the gear-box (the pawl pre- venting its unwinding) and the rubbers extended. A bomb was then placed in the pouch, and on the word or signal to fire a trigger release broke the connexion between the pouch and the wire, and the rubbers, reasserting themselves violently, propelled the bomb.

With a heavy type of grenade weighing ij Ib. the Leach catapult was capable with new rubbers of a range of 200 yd., and like other bombthrowers it possessed the important advantage, as against trench mortars, of invisibility and silence in action. The main disadvantage, the rapid wear of the rubbers, could be overcome by the frequent issue of replacements, the rubbers being re- garded as " consumable " stores. There was, however, a limit to the practical usefulness of this cheap and efficient weapon. Its ranging powers were unnecessarily great for grenade work proper and not great enough for the tasks which came to be assigned to the trench mortar. Accordingly, a lighter and more portable weapon of the same type was designed later bv Capt. G. H. Wicks of the British Trench Warfare Department. This was easily portable and manageable by one man, and ranged, with the I \ Ib. bomb, to about 100 yards. It was, however, not used in the field, as the line had by that time (1916) been drawn clearly between trench-ord- nance projectiles and grenades. The heavy ij lb.-2 Ib. grenade having ceased to exist, the necessity for a weapon to propel it ceased also.

The catapult of the French army, known as the " Sauterelle," was smaller and more portable, but correspondingly less powerful, than the Leach. It was a magnified crossbow, acting by the reassertion of springs bent in cocking.

The " West " spring gun, used by the British army in 1915 and to some extent in 1916, was a heavier and more powerful weapon. It derived its energy from a group of strong coiled springs; for extreme range, no less than 28 of these springs were brought into action. The general principle of action is shown in fig. 2. The weapon having been well bedded in with sandbags for steadiness, the throwing-arm which carries the bomb-cup is forced back-

FIG. 2.

wards and downwards, against the resistance of the springs, by means of a long lever inserted in an appropriate position for lever- age. When the " trigger bar " on this arm engages with a member called the trigger hook (visible in the drawing under the bomb-cup arm), the gun is cocked. The long lever is removed, a bomb placed in the bomb-cup, and the gun is then fired by pressing on the hori- zontal lever which actuates the trigger release. This disengages the trigger hook from the trigger bar, and under the force of the springs the throwing-arm, carrying the bomb, flies up. The range obtained with this weapon using a 2 Ib. bomb was about 240 yd., 24 springs only being in action. Variation of range was obtained, as in the cata- pults, by varying the tension, but also, in this case, by adjustments of the position of the bomb in its cup. The West spring gun was an ingenious design, which probably comes near the limit of efficiency obtainable in applying the force of springs to an act of throwing. But it was heavy, and not very easily managed, and re- quired as large an emplacement as a trench mortar.

The Minucciani bombthrower, though it appeared late in the war after trench engines of the 1915 type had had their day was probably the most efficient and ingenious weapon of its class. It was a large metal casing, circular, supported on a pedestal. Inside the casing was a revolving member, formed somewhat after the fashion of a centrifugal pump. Grenades of a special design (disc percussion) were fed into the " pump " through an opening in the casing, and when the pump was operated by turning a handle, they were expelled by centrifugal force through another opening in the casing. Extraor- dinarily high rates of fire combined with accuracy were obtained with this machine, which could throw the bombs practically as fast as they could be fed in, while, owing to their shape, the grenades themselves ranged well.

Other types of engine developed in the war for throwing grenades differed fundamentally from these in that an explosive propellant was employed. Setting aside certain throwers which are hardly distinguishable from light trench mortars (for which see TRENCH ORDNANCE) and throwmg-devices attached to the service rifle (see GRENADE), there remains a type in which the grenade is formed with a sleeve tail and the thrower consists essentially of a peg over which this sleeve fits, the propellant charge being loaded into the sleeve. The action is thus exactly the reverse of that of a gun or trench mortar. An engine of this type, known as the ' ' Hay pocket howitzer," was experimented with in Great Britain but never adopted as a service store. The Belgian " Van Deuren " type and the German Granatwerfer, on the contrary, were both used in large numbers and the latter especially played a part not only in trench warfare but in the open warfare of 1918 in which it was carried by the infantry in their advance for the purpose of reducing machine-gun nests.

The Granatwerfer of the German army was issued on a large scale, 12 being allowed for each infantry regiment. There were two models, of which the later, that of 1916, is here described.

The equipment comprised the thrower and baseplate (weighing 53 Ib.) and a metal platform (weighing 35 Ib.). The " gun ' (see fig. 3) consisted of a cylindrical firing-peg screwed into a body. This body (which was provided with a carrying handle) had at its rear end trunnions which rested in trunnion seatings fixed to a small baseplate, as in German trench mortars. Elevation was given by clamping the body at the desired angle to an arc on the left side which was rigidly attached to the baseplate. Laying for direction was done by moving the baseplate (and with it the whole system)