Miner's Inch

Arbitrary unit of measure employed chiefly in Cal. to determine the amount of water used in hydraulic mining. In general terms, an inch of water is the quantity that will flow from a flume through each sq. in. of a rectangular outlet in a plank from one to three inches in thickne , when the surface of the water in the flume is kept at a constant height, usually 6 to 9 inches, above the central line of the opening. The amount of water discharged in a given time varies with the head, the size and shape of the opening, and the thickne of the plank. The average effective discharge for each inch may be taken as from 90 to 95 cubic feet an hour. In different States and Territories its value ranges from 1.2 to 1.8 cubic feet per minute. Minerva. Roman godde of wisdom, and patrone of arts and trades; guide amid the perils of war, and helper on to victory; represented as wearing helmet, shield and coat of mail. See ATHENA. IMG:content-1379.png:[blocks in formation] capacity are located to blow up the enemy's works; in the resulting confusion the position is a aulted and carried, as was the case with the Petersburg, Va., mine 1864. To intercept and destroy the besieger's mines, the besieged establish countermines, whose galleries run out from the ditches of their works. When the volume of earth to be blown out is such that the radius of the crater is equal to the depth of the center of the charge, the mine is a common one: under and overcharged mines under the same conditions would require le and greater charges respectively than the common mine.