. Machinery for metalliferous mines : a practical treatise for mining engineers, metallurgists and managers of mines. es.) London : Crosby Lockwood & Son. 4 MACHINKRY FOR METALLIFEROUS MINES. although of great power, with arms of wrought iron, hke the paddle-wheels of a steamer; and as it can be driven at a greater rate than thebreast-wheel, a larger tiuantity of water may be brought to bear upona narrower wheel. It is fitted with curved buckets, deeper than thoseof a breast-v/heel, and without backs or roll boards, so that withinthe rim of the wheel they are altogether open, and as the air ca
. Machinery for metalliferous mines : a practical treatise for mining engineers, metallurgists and managers of mines. es.) London : Crosby Lockwood & Son. 4 MACHINKRY FOR METALLIFEROUS MINES. although of great power, with arms of wrought iron, hke the paddle-wheels of a steamer; and as it can be driven at a greater rate than thebreast-wheel, a larger tiuantity of water may be brought to bear upona narrower wheel. It is fitted with curved buckets, deeper than thoseof a breast-v/heel, and without backs or roll boards, so that withinthe rim of the wheel they are altogether open, and as the air canoffer no impediment to the waters entrance or exit, the buckets aremore numerous and their mouths narrower; one great object in thisdesign being to make the action of the water continuous, avoiding theshock experienced in the undershot wheel; the water enters them nearlyat the lowest point of the wheel, and at a tangent to it, issuing frombeneath a curved sluice, which is opened by being drawn upwards byranks and pinions, as shown in fig. 4. This sluice is nearly in contact with the wheel, so that the broad. Fig. 4.—Poncelets Undershot Watervvheel. stream of water acts directly upon the buckets with all the pressuredue to the head; and as they present themselves in rapid succession,this pressure is almost constant. The sluice is placed in an inclinedposition, leaning as it were against the water, and is held down by radiusbars extending from the back of it to the masonry below; these barsserve not only to retain the sluice in its proper place, but to guide itas it opens or shuts down upon the sill. A wheel on this system 16 ft. 8 in. diameter, and 30 ft. wide, drivenby a fall of water 6 ft. 6 in. high, yielding 120,000 cubic ft. per minute,developed 180 horse-power, when the circumference moved at the rateof II ft. to 12 ft. per second. An ordinary breast-wheel would haveto be 90 ft. wide in order to give the same power under the same con-ditions, so that the Poncelet system
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