. First century of national existence; the United States as they were and onsiderable depthsbelow the surface, by wliich tho labor of removing the superficial deposits is avoided. Veins of ores,whether lying at a steep or gentle inclination, are often explored by such tunnels driven in upon theircourse. Tho sides and roof may he protected or not, as the ground is soft or solid, by timbering. At the outside of tho tunnel below the railroad track is the machine called the long torn, a shallowtrough, ten to twenty feet long, and about sixteen inches wide. Tho lower end, which turns up gent
. First century of national existence; the United States as they were and onsiderable depthsbelow the surface, by wliich tho labor of removing the superficial deposits is avoided. Veins of ores,whether lying at a steep or gentle inclination, are often explored by such tunnels driven in upon theircourse. Tho sides and roof may he protected or not, as the ground is soft or solid, by timbering. At the outside of tho tunnel below the railroad track is the machine called the long torn, a shallowtrough, ten to twenty feet long, and about sixteen inches wide. Tho lower end, which turns up gentlyfrom the plane of the bottom, is shod with iron and perforated with holes. The water from the mine isturned on the upper end, and flows up this slope and through the holes, carrying with it the finer mudand sand which are continually thrown into the tom. One man at the lower end keeps the mud in motionand removes the coarse lumps. Under the lower end of the tom is placed a rifSo box, in which mer-cury may be used to advantage if the gold is in fine particles. T7 ^ ryj ^ts^?. LAKGK ROCKKR USED IN CALIFORNIA WITH QUICKSILVER. Tho above cut represents a rocker of unusual dimensions, wliich has been introduced in some placesin California, and is employed particularly for auriferous deposits in which the gold is in too line particlesto be caught in the long torn. It is slightly inclined, and is rocked by one man while the others collectthe gravel and throw it upon the perforated iron plate. Across the bottom of tho trough are placedriffle bars, and behind each one of these some mercury. The fine particles of gold coming in contaclwith this are caught and retained in the form of amalgam. The coarse gravel falls off the lower end ofthe plate, while the fine mud and sand are washed by the water through the holes in the plate.
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Keywords: ., bookauthorhodgejam, bookcentury1800, bookdecade1870, bookyear1874
