"The flame projectors (Flammenwerfer), which are very similar to portable fire extinguishers, are worked by specially trained pioneers and throw a liquid which at once catches fire spontaneously. The jet of fire has an effective range of 30 meters. The effect is immediate and deadly, and the great heat developed forces the enemy back a long way. As they burn from one and a half to two minutes, and can be stopped whenever necessary, short and isolated jets of flame are advisable, so that one charge is sufficient to spray several objectives. Flame projectors will be mainly employed in street and house-to-house fighting, and will be kept in readiness at the place from which an attack starts." There is no doubt that some engines of this nature were employed by the Germans during August and September, 1914, to destroy portions of the towns and villages destroyed by them. One captured apparatus, actually examined, comprised a portable reservoir for holding the inflammable liquid and the means of spraying it. The former, which is carried strapped on to a man's back, is a steel cylinder containing oil and compressed air in separate chambers. The latter consists of a suitable length of metal pipe fitted with universal joints and a nozzle capable of rotation in any direction. When a valve is turned on, the air pressure forces the oil out of the nozzle in a fine spray for a distance of over twenty yards. The oil is ignited automatically at the nozzle and continues to issue in a sheet of flame until the air pressure falls too low or the oil is exhausted. The heat given out is terrific in its intensity. A similar method employed by the German troops consists of a liquid substance which is squirted into the trenches. Bombs are then thrown which on explosion ignite the fluid. Yet another sort of projectile took the form of an incendiary bomb or shell which was discharged noiselessly, possibly from a catapult. It bursts on impact, tearing a hole and burning a circle of ground about eight feet in diameter.