Firedamp whistle
A firedamp whistle (German: Schlagwetterpfeife) is an instrument for the prophylactic indication of firedamp, flammable gases often present in coal mines. == History == The German Emperor Wilhelm II asked Fritz Haber in 1912, shortly after the opening of the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry in Berlin, for the construction of a warning system for the presence of firedamp.