Page:Pyrotechnics the history and art of firework making (1922).djvu/270

 Recognition and illuminating lights were constructed for use from aeroplanes, and were ignited by dropping through a launching tube fixed to the machine, which made contact and fired them electrically as they passed through.

Landing lights and wing-tip lights, electrically ignited, were other stores used in connection with aerial warfare.

Another was the incendiary bomb. Until the outbreak of war the incendiary composition for use as stars in incendiary shells was of a most primitive nature, and even during the war incendiary compositions were used which were ridiculous in comparison with those produced later.

The construction also of some of the earlier efforts was quite as absurd. Projectiles were devised in a thin paper case, intended to be dropped from heights of many thousand feet, and ignite on impact, whereas the impact produced by the velocity of a projectile after such a fall was sufficient to scatter the case and its ingredients in all directions.

It was the use of aluminium in pyrotechny which pointed the way to real incendiary composition, composition which exceeds the temperature of these primitive pitch and other elementary compositions by many times more than the flame of a candle exceeds the temperature of ice.

Bombs containing thermit, and later on thermalloy (a composition which set hard, and did away with the necessity of a case), were terrible weapons, giving a temperature which has hardly been exceeded by other means.

These compositions were almost identical with some of those containing aluminium used in pyrotechny for a considerable time before the war, but of course not for incendiary purposes. The intense heat is naturally accompanied by brilliant light, which was of great value to the pyrotechnists, the more so as aluminium compositions do not deteriorate on being kept as do those containing magnesium, and although