Democratic Sentinel, Volume 19, Number 16, Rensselaer, Jasper County, 26 April 1895 — Detecting Fire Damp by Sound. [ARTICLE]

Detecting Fire Damp by Sound.

A method of detecting fire damp by sound has been invented by M. Hardy and approved by the French academie des sciences. It is based on the fact that the sound emitted by an organ pipe varies according to the density of the air supplied. M. Hardy’s apparatus consists of two small pipes, the size. of a penny whistle, one of which is connected with the air in the mine and the other with the ventilator shaft. The presence of fire dump produces discord at once between the two sounds, which increases with the quantity of gas which can be measured. By this contrivance the presence of 1 part in 500 of fire damp can be detected.