A light case 52O-lb. bomb has also been made for crater production and for use against submarines. When used in the latter capacity it has a special fuze to obtain " depth-charge " effect, a purpose for which the 65-lb. bomb was used in the early part of the World War. The actual weight of this bomb is 525 Ib. and it carries 340 Ib. of 40/60 amatol. There is also a heavy case 55O-Ib. bomb, with a body of cast steel varying from -75 in. to 1-5 in. in thickness; it carries 180 Ib. of 40/60 amatol. As carrying power is developed, bombs tend to become larger: thus in a recent professional lecture (see Journal of the Royal Ar- tillery, March 1921) a bomb of 1.650 Ib. was spoken of, and even heavier types may be seen in the near future. . ' Incendiary Bombs. In British bombs of present make the following compositions are used : -Thermalloy, which consists of 50 parts magnetic oxide of iron, 27 parts aluminium and 23 parts sulphur; thermite, which consists of 76 parts magnetic oxide of iron and 24 parts aluminium; phosphorus; carcass composition, which consists principally of ground saltpetre, to which is added ground sulphur, sulphide of antimony, black powder and powdered aluminium, mixed with powdered resin, tallow and turpentine. The special match composition for igniters in incendiary bombs is approximately 34% chlorate of potash, 30% iron filings, 5% each of powdered aluminium and nitrate of barium and 26% shellac and methylated spirit. The following are typical incendiary bombs: The modified carcass bomb is made of tin plate, its overall dimensions being 195 in. long by 5 in. maximum diameter. It is tapped at the tail for a pistol. It carries 3^ Ib. carcass and 131 Ib. thermalloy composition, the total weight of bomb and pistol being 23^ pounds. It has two lifting lugs and is carried horizontal. During the loading of this bomb a former is employed to preserve the necessary cavity for the reception of the firing arrangement which consists of the pistol, the special igniter and the adapter and its attachment. The special igniter consists of a 28-bore Eley cap fitted with a copper sleeve containing a strip of instantaneous fuze, and the adapter is a screwed ring socket to which is attached a nozzle-ended celluloid tube loaded with 5 gr. of match composition. On preparation for action the igniter is pushed into the adapter, the latter is screwed on to the pistol which is then screwed into the bomb. The caseless incendiary bomb is made of thermalloy moulded over an iron framework; its overall dimensions are 27-8 in. by 5 in. (side of square of maximum section). The total weight of the bomb is about 30 Ib. of which 24! Ib. consist of thermalloy. The bomb can be stowed either in a vertical or horizontal position, and it is fired by a tail fuze and special igniter. It is fired in a similar manner to the modified carcass bomb, except that in addition to the pistol, special igniter and adapter, a length of instantaneous fuze is placed below the nozzle of the celluloid tube. The baby incendiary bomb consists of three parts, the body, the cartridge and the cap or cover. The body is cylindrical and of thin plate tin, but is weighted at the bottom ; in the centre of this weighted portion is placed a short pin or striker. A little above the latter are two suspending lugs for the cartridge, made by partially cutting out two small portions of the plate on opposite sides of the body and bending them inwards so as to form a support. The cartridge, which is of the ordinary sporting shape, has a percussion cap in the centre of the base and rests on the two lugs. The cap or cover is dome- shaped at the bottom, above which are three vanes with a circular disc on top of them. The assembled bomb weighs about 6 oz. and is about 6 in. long by I in. in diameter. The bomb is carried on the machine with the vaned cap downwards, but on release it turns over and falls with the vaned cap upwards. When falling from heights of over 30 ft. the lugs on which the cartridge rests are on impact sheared or bent sufficiently to permit it to set forward on to the striker, when the cap is exploded and the cartridge case ejected and the thermite ignited simultaneously. These bombs are always used in masses, and are packed in a special carrier which allows them to fall with a con- siderable spread ; thus, to take a particular example, the 272 bombs packed in one form of carrier would, if released at a height of 5,000 ft., cover an area of 30 yd. by 80 yards. The carrier can be dropped complete if it is desirable to get rid of the bombs speedily, as in the case of a forced landing. With large bombing planes like the Hand- ley Page, bombs can be distributed either by using several machines or by successive releases from a single machine. The small bombs provide a many-chance method of attack, which is not possible with the larger incendiary bombs, for with the latter a direct hit must be secured upon a combustible target and the chances are greatly against this combination being achieved. As, however, the small bombs descend in showers with a large spread and on impact further disperse their cartridges over the target area, the chances of a suc- cessful attack are considerable. The 4O-lb. incendiary and smoke bomb can be either burst on impact to produce a smoke screen or burst in air for the attack of kite-balloons, etc. It is made of tin plate -025 in. thick and carries 30 Ib. of phosphorus. Its overall dimensions are I ft. 10-75 ' n - long by 8 in. maximum diameter. It is tapped at nose and tail and has a central tube for a burster containing C.E. pellets and black powder. When used for smoke production a D.A. pistol is screwed into the nose and the tail is plugged, but when an air burst is required the nose socket is plugged and a special time fuze is screwed into the tail socket. The bomb when burst in air spreads out a shower of burning phosphorus over a circle of some 250 yd. in diameter. The lumps of phosphorus slowly burn out in falling and about half are used up in the first 2,000 ft. from the point of burst. If the latter be 3,000 ft. above the target the bomb will be practically lost. The special time fuze employed, the Medgelly fuze, is set in action by a striker, normally held back by a spring in compression, which is released by a trigger when the bomb is dropped. The Ranken Dart. This dart, invented by Engr.-Com. F. Ranken, was used for the attack of Zeppelins and for other purposes. It consisted of a hollow tin cylinder, about the size of a large candle; the bottom was closed by a pointed bullet of steel or iron, and its top by a lid of tin through which passed a spindle capable of vertical movement and terminating at the end outside the dart in four flanges or vanes. The cylinder was filled with incendiary composition which was fired after the fashion of a Christmas cracker. For this purpose a strip of friction match had one end attached to the cylindrical body and the other to the spindle. Then if the dart fell upon a Zeppelin from above, its sharp bullet point would enable it to pene- trate the outer covering upon which, however, the four flanges or vanes would catch ; a jerk would thus be given to the spindle causing the match to be torn apart and ignited, and the dart, held fast in the cover of the Zeppelin, would burst into flames. . Bomb Parachute Flares. These flares are used for reconnais- sance at night, for illuminating and showing up ground held by the enemy, and for affording light to a pilot wishing to land in the dark. The flares are cylindrical paper tubes filled with aluminium composition and primed with magnesium composition; they are sometimes called candles. They are lighted by means of pieces of quickmatch attached to the primed end, the other end being fixed in a cup arrangement which is attached by a wire rope to the parachute. Electric-Ignition Parachute Flare-Bombs are of two kinds almost similar in construction. One is used as a reconnaissance flare, the other as a landing flare to enable pilots to land in the dark. They are both launched by means of a launching tube attached to the fuselage of the aeroplane, and so designed that as the bomb leaves the launch- ing tube an electric circuit is completed, and a platinum-silver wire bridge heated. This, by igniting a priming, sets a delay pellet in action and, after the bomb has dropped some 1,000 ft., a powder puff is fired, which both ignites the candles and projects the parachute clear of the cylinder. The reconnaissance flare (with a 9 seconds' delay pellet) burns for three to four minutes, weighs 6 Ib. 13 oz., and has a parachute weighing n oz. and measuring about 5 ft. 6 in. across when open. The landing flare weighs 5 Ib. 45 oz., and has a parachute of the same size as the other but of lighter material, weighing only 35 oz. The candles burn for from 2j to 3! min.. and the delay pellet only gives one sec. delay so that the bomb opens after it has dropped some 20 feet. In both bombs the candle power is about 40,000. (J. R. J. J.) German Air Bombs. The general characteristics of air bombs being the same in all countries, British practice may be regarded as typical and foreign bombs need not be dealt with. Some notes on German air bombs are added, however, on account of the special interest attaching to these projectiles, which for the first time for many centuries brought war to the very doors of the British people. The earliest types designed by the Germans were so far ineffective that as early as the spring of 1914 they were replaced by bombs of a type known as " Carbonite." These bombs, which were used through- out the earlier part of the war, were pear-shaped and solid, pointed, and had a propeller-actuated pistol of the same type as those described earlier in this article. Their special characteristic was the form of air-drag used : instead of fins, a sort of inverted tin cap was used, attached to the tail of the bomb by stays. The smallest of these bombs weighed 43 kgm. (about 10 Ib.), and the heaviest 50 kgm. (no Ib.). Small incendiary bombs of the carbonite type were also used. There was, further, a grenade-like projectile thrown by hand, which weighed 800 grammes (1} Ib.), but this was criticized as being too small to be effective, as also was the 4^ kgm. H.E. carbonite bomb. In 1916, these bombs were replaced by a different type known as " P. und W.," which continued in use to the end of the war. They were torpedo-shaped 1 and were fitted with slanting vanes which not only acted as an air-drag to keep the projectile nose down but also imparted rotation to the falling bomb, and so enabled the German designers to replace the propeller as an arming device by centrifugal bolts, on the same principle as those of gun fuzes. As the height at which bombs were released had by that time greatly increased, the additional time required for the arming of the fuze was of no im- portance. Time fuzes were also employed, chiefly for obtaining delay effects after impact. The standard sizes of these " P. und W." bombs were the I2j kgm. (27 Ib.) a thick-walled bomb with instantaneous fuze and the 50, 100, 300 and 1,000 kgm. " mine" or thin-walled bombs, with bursters respectively of 23 kgm., 60 kgm., 180 kgm., and 680 kgm. One other form of air projectile should be mentioned as, although it was never used on any large scale, it had a moment of notoriety
Torpedo-shaped bombs were also used by the French, who
named them " pisciforme " (fish-shaped) bombs, in contradistinction to " piroforme " (pear-shaped).