MEASURING MINE VENTILATION
I At the Cardiff meeting of the British i Association, Professor Mncgregor-Morris .' described a most ingenious instrument, which gives direct readings of the speed of air ourrente. It is based on a simple clootvical principle. When an eleotrio current passes through n wire, the wire becomes heated, and its electrical resistance changes accordingly.* By using two ideuticnl wires, both carrying the 6ama current, and by protecting one from the cooling effect of wind, the difference of electrical resistance between tho protected wire and tho unprotected wire affods a measure of tho cooling effect and thus of the speed of the wind. On these linos .the inventor has devised a portable apparatus which' reads directly in miles \ per hour with remarkable accuracy. The i chief uso of this apparatus is for meas- | Tiring tho ventilnlion of coal mines, but I it has many other applications.
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Dominion, Volume 14, Issue 41, 12 November 1920, Page 7
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147MEASURING MINE VENTILATION Dominion, Volume 14, Issue 41, 12 November 1920, Page 7
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