and being forced back on to the detonator when the object is struck. To ensure this action, in the case of grenades, the outer end of the pellet is usually formed with a large disc or mushroom head which augments the surface of impact and therefore the resistance which tends to drive in the pellet.
FIG. 4
A simple grenade of this kind is the " Japanese " grenade as employed by the Russian army in the World War (fig. 4). This is a heavy-bodied fragmentation grenade with a hood bound on by cord wrapping instead of streamers. It will be seen from the draw- ing that when the safety ring 6 is removed nothing holds the striker 5 away from the detonator cap except the tightness of fit of .the striker rod in the india-rubber block 8. On impact the mushroom head 9 forces the striker in and the grenade is fired. This was a rather light grenade weighing about I Ib. 4 oz. and ranged, in expert hands, to about 45 yards. It could not be used in the open, as frag- ments came back as far as 200 yards. It had no handle, being grasped by the body.
Time grenades, as already explained, possess the advantages of intrinsic safety and of being able to act in any position of fall, though in other respects inferior to percussion. The types described below have been selected (a) to show the variety of ignition devices employed and (6) to indicate the evolution of design generally during the war period.
The type of grenade shown in figs. 5 and 5a is a Russian pre-war design, based no doubt on Port Arthur experience. The model shown was brought out in 1914 to replace an earlier and heavier engine of similar design.
Between the detonator and the cap is a column of slow-burning composition 21 connected to the cap 19 by strands of quickmatch 25. As in almost all patterns of grenade, the detonator element is transported separately. In this case the parts which render the grenade " live " are assembled in a U-shaped body 18 which is dropped into position with the cap over the striker 6 and the detona- tor 22 in a cavity in the exploder 23, and clipped there by the fastener 20. The action is as follows: the bomber grips the handle, pressing on the lever 12, and thus by means of the sear a cocking the striker-spring 8 and striker 6. His fingers encircle the safety- ring 15 (which has hitherto held the lever) in such a way that in throwing the grenade the ring will remain in his hand. He then withdraws the safety-pin II which limits the forward movement of the striker. When he throws the grenade, the spring 14 forces out the lever 12 and the striker 6, released from the sear a, flies forward under the influence of its spring and fires the cap. This, through a flash along the quickmatch 25, starts the slow-burning composition which in due course fires the detonator, exploder, and main charge. Though primarily a thin-walled " concussion " grenade, this pat- tern has the casing lined with metal rings 17 prepared for fragmenta-
FIG. 5
5, FIG. 5a
tion. 1 It will be noticed that the handle portion as well as the body proper is filled with explosive. Carrying nearly I Ib. of H.E., this was a very formidable concussion grenade, serviceable and not too difficult to manufacture (in spite of its apparent complexity), and could safely be used in fighting in_the open.
10
FIG. 6
In marked contrast to this grenade are the more or less impro- vised time grenades of 1915 of which the British " cricket ball," the French " Fl " and some German specimens may be taken as representatives. The British " cricket ball " (fig. 6) and its variant the " lemon " was a plain iron, spherical or ovoid shell into which was screwed a plate carrying a detonator sleeve. In preparing for action the detonator was placed in the sleeve and secured by wire. Crimped into the mouth of the detonator was a 5-seconds length of Bickford safety fuze, the other end of which was prepared with a patch of composition such as is used for safety matches. The pro- tective cap 8 being pulled off, the grenade was ignited by rubbing the head against a strip of matchbox composition (tied on the bomber's sleeve), and thrown. The weight of this grenade in its cricket-ball form was ij Ib.
The French " defensive " (i.e. fragmenting) grenade " Fl " weighed Ij Ib. As shown in fig. 7 it was ignited by a blow. The cover 10 being removed, a sharp blow on the cardboard inner tube 4 (carry- ing the cap) forced the cap down on the striker, igniting the time- fuze length 8.
The German 2-lb. ball grenade (fig. 8), unlike most, was powder- filled and, as it could therefore be fired by a flash, needed no sensi-
1 The earlier (2j-lb.) pattern had a large amount of " langridge " (i.e. small pieces of metal) packed round the explosive charge.
