MINING. 307 



In calculations made by machinists it is often necessary to 

 use the term " an inch of water," and by common consent 

 that phrase is accepted now to mean a supply of two and one- 

 third cubic feet of water passing a given point in a minute of 

 time, equivalent to 21,000 gallons in 24 hours. The mining 

 ditches of the State carry 171,000 inches in the aggregate, but 

 much of this is used for only ten hours a day, and we may 

 consider it equal to 100,000 inches running 24 hours, or 2,000,- 

 000,000 gallons a day, more than all the great city aqueducts 

 of Europe supply. Single hydraulic claims use 3,000 inches 

 each, or 60,000,000 gallons daily ; or more than New York 

 City with nearly a million inhabitants gets from Croton 

 aqueduct. The price of water, as sold by the mining ditch 

 companies, varies from five to twenty cents per inch for ten 

 hours, the average being about ten cents. 



227. Gleaning up. The separation of the gold, amalgam, 

 and quicksilver, from the dirt in the bottom of the sluice, is 

 called " cleaning up " ; and the period between one " clean- 

 ing up " and another is called a " run." A run in a common 

 board-sluice usually lasts from six to ten days ; in a large hy- 

 draulic claim, one month. Ordinarily the sluice runs only 

 during daylight, but in hydraulic claims the work continues 

 night and day. Cleaning up occupies from half a day to three 

 days, and therefore must not be repeated very often, because 

 it consumes much time. In some sluices the cleaning up 

 does not occur until the bed of the sluice has been worn 

 out or much bruised by the wear of the stones and gravel. 

 Cleaning up in small sluices is considered light and pleasant 

 work, and is often reserved for Sunday. At the time fixed 

 the throwing in of dirt ceases, the water runs until it becomes 

 clear, the false bottom of the sluice is taken up in sections, 

 and the heavy sand, amalgam, and quicksilver, taken up in 

 pans. After separating the sand, the quicksilver and amalgam 

 from the sluice are put into a buckskin cloth, and pressed, so 

 that the liquid metal passes through, and the amalgam is re- 



