Page:Pyrotechnics the history and art of firework making (1922).djvu/275

 is generally wrecked on a lee shore, so that in firing from the ship the rocket travels with the wind.

Both the Brock and Schermuley systems are designed for this purpose, and there is little doubt that in a few years all vessels will carry their own means of establishing communication with the shore.

As a further development of the line-carrying rocket, it is interesting to note that Congreve, in association with Lieut. J. M. Colquhoun, took out a patent for the use of the rocket as a harpoon in whale fishing, which, if it proved satisfactory in use, must have been a marked advance, especially as this was before the advent of the now universally used harpoon gun.

Another pyrotechnic invention responsible for the saving of many lives is the Hale's Light apparatus. This apparatus is fitted to a lifebuoy, which is arranged for launching from a vessel's bridge; the act of launching ignites a flare, enabling the person in the water to see the buoy and the rescuing boat to pick them up.

The practical use to which fireworks have been put on land are many. Probably that which comes most readily to the mind is the sound signal or alarm. Many fire brigades whose members are volunteers and therefore scattered use aerial maroons to warn and call them for duty. These maroons became familiar to Londoners during the air raid period in the late war.

The maroon has also been adopted for firing with a trip line as a burglar alarm, or for protecting game preserves or similar purposes.

Another well-known pyrotechnic sound signal is the fog signal used on the railways, which consists of a tinned iron envelope containing a mixture of chlorate of potash and red phosphorus. It is secured in position on the rail by two lead