3/10 GEOLOGY OF OHIO. 
CASTELLO’S ANEMOMETER. 
Approximate measurements are made by miners by flashing gun- 
powder, and noting with a watch the speed with which the smoke 
moves along the air-way of the mine. A lighted lamp is sometimes 
used, the miner moving along the air-gallery, and keeping the light in 
a perfectly perpendicular position, noting the time required to pass to 
a given point. Both of these methods are the same in principle. The 
experiments can only be made along a straight gallery of uniform area. 
The distance measured off is usually from 100 to 200 feet. The lineal 
feet of the air-way is ascertained, which, multiplied by 60, the number 
of seconds in a minute, and divided by the number of seconds of time 
in which the powder smoke moved or the person traveled the measured 
off distance, gives the amount of cubic feet of air per minute in circu- 
lation. 
