Stokes’ Mortar
Another British invention is the Stokes’ gun or trench mortar. The range of this gun is about 800 to 1000 yards. It is therefore effective only where the front lines are relatively close together. The shell consists of a case containing the high explosive, smoke material or gas, fitted to a base filled with a high charge of propelling powder. The shell is simply dropped into the gun. At the bottom of the gun there is a projection or stud that strikes the primer, setting off the small charge and expelling the projectile. In order to obtain any considerable concentration of gas in a particular locality, it is necessary to fire the Stokes’ continuously (15 shots per minute being possible under battle conditions) for two to five minutes since the bomb contains only seven pounds of gas.