MEASURING MINE VENTILATION.

Pukekohe & Waiuku Times, Volume 9, Issue 589, 3 December 1920, Page 3

MEASURING MINE VENTILATION.

J At the Cardiff meeting of the Brii tish Association Professor Macgregor Morris described a most ingenious instrument which gives direct readings of the speed of air currents. It is brsed on a simple electrical principle. When an electric current passes through a wire, the wire becomes heated and its electrical resistance changes accordingly. By using two identical wires, both carrying the same current, and by protecting one from the cooling effect of wind, the difference of electrical resistance between the protected wire and the unprotcted wire affords a measure of the cooling effect and thus of the speed of the wind. On these lines the inventor has devised a portable apparatus which reads directly in miles per hour with remarkable accuracy. The chief use of this apparatus is for measuring the ventilation of coal mines, but it has many other applications.