|
30
GOLD UIXIXG IX XOETH CAKOLIXA.
The rockers in use to-day are of two types. The first is essentially a panning process, using a minimum amount of water, the operation being an intermittent one. This type of rocker is (dosed at both ends, the discharge being over the side; it will be described, with illustrations, as now in use at the Crawford mine (p. 91). The second type consists of a hollow segment of a log closed at the upper end. It is set on a slight inclination, about 6 inches in 10 feet, and is provided at the lower end with grooves or strips that act as mercury pockets or riffles. AVhen used on gravel it is provided at the upper end with a shallow box having a round punched or slotted iron bottom. The length of this type of rocker is 5 to 10 feet. The gravel and clay are thrown into the box, where a constant stream of water, together with the rocking motion and stirring with fork or shovel, disintegrates the material. The pebbles and bowlders are thrown out with the fork, while the fine portions are washed down the bottom. The rocking facilitates the settling and amalgamation of the gold and the discharge of the tailings. Two men work at one rocker or set of rockers, so joined together as to move in harmony. One throws the gravel from the pit into the box, or directly into the rockers, and the other sits or stands above the rockers moving them with his feet, disintegrating the gravel with a fork and discharging the coarse material. Rockers of a similar type are at present in use at several mills for handling pulp and blanket washings. (See Plate I.)
"Where sufficient flowing water is at hand, the sluice box and long torn are used, as they handle larger quantities with less labor. The sluice box, generally 8 to 10 feet long, 20 inches wide and 12 inches deep, provided with riffles and a perforated charging plate at the head, fulfils the same purpose as the rocker; being stationary, however, it requires a larger amount of water to carry off the tailings.
It is interesting to note that at the Beaver Dam mine, in Montgomery county, X. C, a large rocker, about 10 feet long by 3 feet wide, was ojieratcd as early as 1825 by steam power, the engine having been imported from England.
Tuomey,1 in 1854, mentions ground-sluicing of side-hill deposit* at Arbacoochee, Ala., by aid of a ditch and a series of trenches into which quicksilver was poured. It is probable that this method of working existed even prior to that day.
HYDRAULIC METHODS.
The first use of the hydraulic method of mining was probably early in the forties, previous to the California gold discoveries, in the western part of Xorth Carolina, although on a much smaller and modified
1 Second Biennial Report on the Geology of Alabama, p. TO, Montgomery, 1858.
|
||
|
|
||