Barlow United Gold Mines and Hydraulic Works of Georgia, have, however, been lately using the whole amount in working their own mines. Besides this system there are several smaller ones, bringing the total length of ditch-lines up to about 80 miles.
A unique feature of the water-supply at the Findley mine is the elevation of the water from the ditch-line to a reservoir situated 152 feet above it, by means of a hydraulic pumping engine made by the Filer & Stowell Company, of Milwaukee, Mich. This pump is situated near the stamp-mill, 285 feet below the ditch-line. The water is led to it from the above ditch in a 16-inch straight-riveted feed-pipe 456 feet in length, and is discharged by it into a reservoir of 88,000 cubic feet capacity, a total vertical height of 437 feet, through a 12-inch steel pipe 1141 feet in length. The principle involved is that of the hydraulic ram, inasmuch as a large quantity of water under a lower head raises a certain portion of itself to a higher head, the remainder being waste. The machine, however, is of entirely different and, so far as known, novel construction. It is of the duplex pattern, the two engines being •connected by gearing and with an 8-foot fly-wheel. Each engine has 3 cylinders in tandem, to which the water under the feed-head (123 pounds) is admitted and discharged by valves of the Biedler type. In one of these cylinders the water is raised to the greater head (190 pounds) at the expense of the feed-water, under head, going to waste in the other two. A snifting-valve is attached to the latter to give relief to the valves. The stroke is 18 inches, and at a high piston-speed of 250 feet per minute the pump works very smoothly. Tests had not been made, and no figures of efficiency could be obtained at the time of our visit. Such figures, as well as a more detailed description than could lie made after a hasty examination, would be of great interest. The present working capacity of the pump is 600 gallons per minute.
MINING METHODS.
The general character of the ore-bodies has already been described (pp. 22 and 23). The depth of the saprolites (decomposed schists) in the Dahlonega region reaches often to 50 and sometimes 100 feet. Enormous openings have been made in these by the hydraulic giant, wdiole sides of the mountain being torn off in places (see Plate IX). The head employed in hydraulicking varies from 50 to 150 feet, dependent on the height from which water can be obtained. "Where harder rock is torn loose, it is broken by hand-sledges and thrown into the groundsluices. Powder is sometimes resorted to for breaking down the more resistant ledges. In order to shorten the distance in sluicing to the mill, tunnels are often run through the intervening hills (as at the Hand and Findley mines). The Avooden sluice-line is supplied with longitudinal riffles throughout its entire extent.
