In addition to the several modes of working the apparatus explained, it is proposed to work the same in streams, or ponds, where gold-dust, ores, etc. may be found, or suspected to exist, without using a tub, in which case the agitator only is to be used, and must be supported, as before, by its cross-bearers D D, and standards CC. Figs. 1, 2, 3, 5, 6, being either fixed to the bottom of a boat or punt, or supported between two boats or punts, the same being immovably moored or fixed upon the water; or he machinery may be placed upon a stage with legs, adjustable to the depth of the water, so that the agitator may be put into rapid circular motion as before described; or as near as possible to the bottom of such river or stream, when it will soon, by such motion, remove the soil (provided it is not too hard or strong), and will form itself into a circular hollow space equal to its own diameter, into which space it is to be gradually lowered as the earth is washed away; when, if any gold-dust, ore, or heavy metals are present, they will be brought to the centre thereof as effectually as if the first agitator had been worked in a tub; which done, the position of the central spindle of the agitator is to be worked as accurately as possible, either upon the stage that supports it, or by placing upright straight rods in the ground round about it, when a light metal tube, of tinned or plate iron, open at both ends, and of equal diameter to about one-fourth of the agitator that has been used, is to be lowered over the said central spot, for the purpose of confining and covering whatever may have been so brought to the centre, which may then be raised in the tube, by inserting a pump therein till it reaches the sand; and after having made with it a partial vacuum by raising this pump, the whole tube is. brought out with it; or by means of proper ladles, augers, screw-worms, or other implements used for boring the earth, and bringing up the same though tubes for well-sinking, and other well-known purposes; or the implement shown at Fig. 8 may be used to advantage.
It consists of an hexagonal, or other polygonal pipe of iron made nearly to fit and fill up the inside of the light pipe before mentioned (directed to be lowered for covering and securing the materials); its lower end is to be formed into as many points as the first polygonal has sides, as at a a a a in Fig. 8; these points should be of steel, not only for durability, but that they may bend inwards and spring open again in the form shown at X, in which state the pipe is to be lowered into the tube above mentioned, and it must he pushed through the soil, or whatever the agitator may have brought to the centre, by slackening and turning it round; while, at the same time, the central chain which communicates by branch chains with each of the first points, as seen at Y, is to be strained with sufficient force, either by the lever Z or in any other way, to bring all the first points a a a, etc. together, in which state they will be retained, until the contents thus confined to the pipe are brought up out of the water, and discharged on the boat or platform.
Having now described a variety of processes for obtaining the ores of copper, lead, tin, gold, silver, and some other metals, we will refer the reader to the article Coal, (Vol. I. pp. 374 and 375,) where a sectional engraving of a coal mine and iron mine is given, with an accurate description of the mode of working the same. It is an astonishing and highly interesting sight to a stranger in the neighbourhood of Birmingham, and in other coal and iron districts, to behold, at one view, a great number of steam engines, with all their massive machinery and apparatus, simultaneously at work in the open air; some employed in drawing up the iron ore, others coal; which, as they emerge from the earth, are sometimes lifted upon an elevated rail-road, from whence, by their own gravity, or by the aid of machinery, they are conveyed with rapidity to their destination; the contents are instantly discharged, and the emptied skip brought back in continuous succession.