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This mounting marks about the limit of possible weight for an automobile gun-carriage. In fact, it is only fit to travel by rail to a point near its destination, and thence to travel by main roads and across country, avoiding by-roads and country bridges. It may be noted that the 6o-pdr. gun-carrying caterpillar tried by the British weighed 35 tons with the gun and had to be discarded as too heavy. The ordinary road bridges of a country, other than those on the main " national " roads of western Europe, will not carry more than about 20 tons, and ordinary road culverts are liable to be crushed. The simplest solution of the difficulty is to transport the gun and carriage separately, as with the German 15-cm. 43-cal. gun.

The 8-in. Howitzer. Early in the war it was found necessary to introduce for field service a howitzer firing a shell of about 200 lb., for the destruction of fortified buildings, railway stations, and bridges. Non-mobile weapons of this class were already in existence

FIG. 33.

8-in. howitzer, Mark VII.

as siege pieces, and these were employed with modified mountings, as a makeshift. But the Germans in particular had developed wheeled mountings for 2i-cm. " mortars," and the appearance of these as mobile heavy artillery obliged the Allies to follow suit.

The British at first issued an old-pattern 6-in. gun with the muzzle cut off, bored out to 8 in. ; this was superseded by the Mark VII. 8-in. howitzer shown in fig. 33. Some of these British pieces were used by the French and Americans. The howitzer was 18-5 cals. long and weighed 69 cwt., or 10-3 tons on wheeled carriage. It was an enlarged edition of the 6-in. howitzer, and ranged 12,500 yd. This piece could be transported by road, the carriage travelling empty; this weighed 6-8 tons. A platform was provided for use in soft ground. The Americans, when they adopted this piece, mounted it on an automobile carriage (which also took the 6-in. gun) made by putting the urjpcr carriage of the howitzer on an 8o-H.P. Holt caterpillar. This mounting gives 45 elevation and 8 traverse, and weighs 26 tons complete. The road speeds are I to 4 m. an hour.

FIG. 34. German 2l-cm. howitzer, or " long mortar."

The U.S.A. 1920 model 8-in. howitzer is more powerful than the British Mark VII. It is 25 cals. long and weighs 80 cwt.; it fires a 2OO-lb._ shell, M.V. 1,950 f.s., ranging 18,000 yd. The wheeled carriage, which also takes the 6-in. gun, gives 65 elevation and 10 traverse on the axle; it has variable controlled recoil, the full recoil being 6 ft. The elevating gear consists of 2 toothed arcs which can be released from the cradle trunnions so that the howitzer can be swung to the horizontal position for loading. The weight is 1 1 tons.

The French had no mobile 8-in. howitzer before the war. They issued a certain number of ig-cm. guns bored out to 8-in. calibre (not cut short) to fire British 8-in. ammunition. These guns on high- angle carriages made good long-range howitzers and were used on railway mounts, but were too heavy for road transport. For a mobile piece the French introduced the Schneider 22-cm. (S-ay-in.) siege howitzer, 13 cals. long, firing a 2i6-lb. shell, M.V. 1,120 f.s., and ranging 9,600 yd. ; the method of transportation was peculiar to the French artillery, the howitzer itself being fitted with road wheels and a perch instead of being carried on a special wagon like the xxxi. 39

German heavy howitzers. The howitzer with wheels weighed only 2} tons, and the empty carriage 3j tons, making loads which could be transported by horse draught or by a small tractor. This howitzer is fired from its wheels, and can be fired from the bare ground, but requires a platform for continued fire.

The German 2l-cm. (8-3-in.) howitzer, styled a " mortar," was of several- patterns. The very earliest fired from a bed, but the pieces which played a conspicuous rdle in the war were the ordinary or short mortar 12 cals. long, which ranged 9,800 yd. with 265-lb. shell (M.V. 1,120 f.s.), and the long mortar was 15 cals. long and ranged 11,200 yd. with 26i-lb. pointed shell. The recoil gear consisted of 2 oil buffers and an air recuperator, placed above the piece, allowing 43- in. recoil. The carriage gave 70 elevation and 4 total traverse. The short mortar weighed 2-6 tons, the long pattern 2-8 tons; the weights in action were 6-3 and 6-5 tons respectively.

FIG. 35. British 9-2-in. Mark II. howitzer (" Mother ").

9-2-in. and p-45-in. Howitzers. The British 9-2-in. howitzer was a pre-war design, and the first of these equipments were sent to France in November 1914. Fig. 35 shows the general construction. It fired a 2go-lb. shell ranging 10,000 yd., but with a pointed shell a range of 12,700 yd. was afterwards obtained. This was the first British equipment to be provided with a floating piston.

The howitzer was 14-6 cals. long and weighed 3-1 tons; the car- riage weighed 5-3 tons, but this weight could be reduced for travelling by carrying the cradle separately. This wheeled mounting allowed the howitzer to be fired at angles between 15 and 45 elevation. This feature, namely, restricting the fire to the higher angles of elevation, is found in most heavy howitzer equipments on wheels; the object is to avoid the extra weight and extra length of recoil which would be necessary to keep the carriage steady if the howitzer were fired point-blank. The howitzer traversed on the axle, 2j- either way. It could be fired from the bare ground, but a platform was generally laid for it. Some of these howitzers were mounted on beds instead of

FIG. 36. U.S. Mark IV. carriage for 9'45-in. howitzer.

firing from their wheels; the platform for these had a pivot in front, an arc in rear to support the rear of the bed, and a pit into which the breech of the howitzer recoiled.

The true 24O-mm. howitzer was not much used in the war; it is an intermediate piece which lacks the shell-power of the larger calibres and is nearly as troublesome to transport and to emplace. However, the U.S.A. has a new howitzer of this calibre, 36 cals. long, M.V. 2,350 f.s., which ranges 25,000 yd. with 356-lb. shell. This is really a gun, though called a howitzer. Many old, short naval guns of this calibre were used by the French during the war practically as long howitzers.

A very interesting automobile mounting for a 24O-mm. howitzer was brought out by the French firm of St. Chamond during the war. This consists of a caterpillar mounting drawing a power trailer behind it. The trailer carries a petrol engine and dynamo which supplies current to the electric motors, both of the mounting and the trailer. These two may be connected mechanically and electrically, or electrically only by a cable. Thus if the drawbar be disconnected the trailer may remain behind under cover and drive the gun-