THE MINERS' INCH 



211 



slot there is a closely-fitting block, made to slide on the beveled 

 edges and fastened by a screw to the sliding board. It is obvious, 

 then, that when the sliding board is moved backward or forward, 

 by means of its end, which is extended for a handle, the block 

 moves in the slot and determines the length of the opening. 



In operation the board is placed in the stream as shown in the 

 figure, so as to dam the flow completely, and the sliding board is 

 moved backward or forward until the water is all passing through 

 the slot, the water being kept up to the top of the board, or 4 

 inches above the center of the opening. The length of the opening 

 measures the number of miner's inches of water flowing through. 



Measuring miner's inches in a small stream or ditch. 



If the flow is too great to pass through the opening 1 inch wide, 

 the opening may be made wider, the water still to be kept 4 inches 

 above the center of the opening. The laws of several States 

 provide that in devices for measuring water for sale by the miner's 

 inch the opening shall be 6 inches high and shall be provided with 

 a slide as shown in the picture. The number of miner's inches 

 then discharged is equal to the number of square inches in the 

 opening. The assumption made that the discharge is proportional 

 to the size of the opening is not true, but the error in measuring 

 small quantities is not great enough to be taken into consideration. 

 By converting the results of measurements in miner's inches to 

 gallons, cubic feet, or some other familiar unit, it may be deter- 

 mined how long it will take the stream to fill a reservoir or cover 

 a given field with the necessary depth of water. This unit is readily 

 convertible into cubic feet or gallons or acre-inches of water, 

 according to the time the water flows. 



The following data will be helpful in computations : One 

 miner's inch, as described above, equals 0.1496 gallons per second, 

 8.976 gallons per minute, 538.56 gallons per hour, 12,925.44 gallons 



