Alarm Signals
Numerous, indeed, were the devices invented at one time or another with which to sound gas alarms. The English early devised the Strombos horn, a sort of trumpet operated by compressed air contained in cylinders carried for that purpose. Its note is penetrating and can be heard, under good conditions, for three or four miles. When cloud gas attacks, which occurred only at intervals of two to four months, were the only gas attacks to be feared, it was easy enough to provide for alarm signals by methods as cumbersome and as technically delicate as the Strombos horn.
With the advent of shell gas in general, and mustard gas in particular, the number of gas attacks increased enormously. This made it not only impossible, but inadvisable also, to furnish sufficient Strombos horns for all gas alarms, as gas shell attacks are comparatively local. In such cases, if the Strombos horn is used to give warning, it causes troops who are long distances out of the area attacked to take precautions against gas with consequent interference with their work or fighting.
To meet these local conditions metal shell cases were first hung up and the alarm sounded on them. Later steel triangles were used in the same way. At a still later date the large policeman’s rattle, well known in Europe, was adopted and following that the Klaxon horn. As the warfare of movement developed the portability of alarm apparatus became of prime importance. For those reasons the Klaxon horn and the police rattle were having a race for popularity when the Armistice was signed.
A recent gas alarm invention that gives promise is a small siren-like whistle fired into the air like a bomb. It is fitted with a parachute which keeps it from falling too rapidly when the bomb explodes and sets it free. Its tone is said to be very penetrating and to be quite effective over an ample area. Since future gas alarm signals must be efficient and must be portable, the lighter and more compact they can be made the better; hence the desirability of parachute whistles or similar small handy alarms.