As reported by Bob Werner and Tony Brewis (and Peele), the miner's inch did
vary considerably from one (U.S.) state or even district to another -- and it
even varied in one place over time.
Eugene Wilson's "Hydraulic and Placer Mining" (3rd Ed., 1918) states in part:
"The miner's inch, up to the year 1905, was very confusing, as each ditch
company in California at least had a water inch of its own. The miner's inch
in California is now 1.5 cubic feet per minute, or 11.25 gallons per minute."
Augustus Bowie's "Practical Treatise on Hydraulic Mining in California" (11th
edition, 1910) states:
"The miner's inch of water is a quantity which varies in almost every
district in California; no one gauge has been uniformly adopted, nor has any
established pressure been agreed on under which the water shall be measured.
In some counties there are 10, 11, or 12 hour inches, and in others there is
a 24-hour inch. The apertures through which the water is measured are
generally rectangular, but vary greatly in width and length, being from one
inch to twelve inches wide and from a few inches to several feet long. The
discharges are through 1-inch, 1 1/2 - inch, 2-inch, and 3-inch planks, with
square or with square and chamfered edges, combined or not, as the case may
be. The bottoms of the openings are sometimes flush with the bottoms of the
boxes, sometimes raised above them." etc., etc.
If one regards the miner's inch as a somewhat "loose" unit of measurement, I
would refer to the USGS Water-Supply Paper on Water Resources of Hawaii
(1913). Therein a unit entitled "man's water" is described as "an irrigator's
term" in common use in Hawaii: "It signifies the amount of water that one
irrigator can properly handle in the field. It varies greatly, being
dependent upon the condition of the furrows, the age of the crop, and the
skill and individuality of the irrigator."
(Incidentally, miner's inch is defined in this USGS publication as follows:
"the unit for the rate of discharge of water that passes through an orifice 1
inch square under a head which varies locally. It is commonly used by miners
and irrigators throughout the West, and is defined by statutes in each State
in which it is used.")
I do not know if there is a precise metric conversion for either the miner's
inch or for man's water. If so, perhaps such a quantity is displayed under
glass in Sevres by the BIPM (International Bureau of Weights and Measures).
Noel Kirshenbaum (California)
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