HEIGHT of 20 Feet Greatest DANGER LEVEL from Ground EXPLOSIONS

Sun (Christchurch), Volume IV, Issue 1164, 3 November 1917, Page 12 (Supplement)

HEIGHT of 20 Feet Greatest DANGER LEVEL from Ground EXPLOSIONS

lery projectiles are of that class: however, the word is often incoi*rectly used. The dictionary defines shrapnel as "a shell filled with bullets and having a bursting charge to explode it at any time in its flight." This definition has been credited to a British officer, but, while accurate, other authorities say it is misleading. It describes the inside of a shrapnel well enough. The bullets, technically shrapnel, are imbedded in rosin and fill the Isteel casing above the diaphragm which closes up the powder pocket in the base of the casing. In this powder pocket is confined the powder charge which "explodes" the shrapnel. A timing device, from which emanates the flash which ignites the powder charge at some predetermined instant, caps the- shell casing and forms the nose of the shrapnel. All this has become familiar enough to many within the last few years, with the possible exception of the timing device and its operation. On firing a gun loaded with shrapnel, the cartridge case is left behind, just as is the shell when discharging an ordinary shotgun. The complete shrapnel, with Fits time fuse, etc., is projected at a high rate of velocity, revolving rapidly in its flight and travels as a unit until such instant as the flash from the fuse explodes it. A shrapnel which breaks properly during flight simply scatters shrapnel

balls, not fragments and pieces or jagged shell such as fly from an exploding high-explosive shell. When a frhrapnel, through failure of the time fuse to respond, does not explode until it comes in contact with the ground or some other firm object in its path, then, and only then, the steel shell is fractured and pieces scattered in all directions. Damage frequently described as caused by flying pieces of shrapnel casings, therefore, is more probably correctly to be ascribed to fragments of highexplosive shells. A properly built shrapnel can be timed to break accurately at any predetermined distance in its flight, notwithstanding the; that on

leaving the muzzle of the gun it may be traveling at a speed of close to 2000 feet per second. The time fuse controlling this all-important function is carried on the end of the shell casing and forms the nose of the projectile. Different types of fuses are employed, but one kind, a combination detonator and time fuse, is simple and well illustrates the principle involved. " Adjustment of the timing ring regulates the time required for transmitting the flash of the sensitive explosive on the end of the explosive slug to the powder under the diaphragm, so that the shrapnel will break at any. predetermined point in its flight. This regulation is aecbm-

plished by simply increasing or decreasing the length of fuse wtych has to be consumed between the point at which it is ignited by the flash from the explosive slug and its connection to the train leading to the guncotton. On striking, the explosive slug is thrown violently forward by the concussion and in moving forward opens communication to the Jipper of the two powder trains, so that the flash of the sensitive explosive ignites this more direct train. This explodes the powder charge in the pocket instantly, as no time is wasted in- the preparatory consumption of the encircling fuse within the time ring.