Illustration: (‡ PLOUGH.) The plough has been in use from the very earliest ages, and has been but little altered for many centuries; it is drawn by horses attached to the chain A at the end of the “beam,” and guided by a man holding the “stilts” or handles B B, the coulter, C, cuts a perpendicular slice in the ground, and the “share” or “slade,” D, following, cuts horizontally, so as to separate a long piece of earth which the breast or mould-board E, placed obliquely, turns over on one side; the plough returning at regular distances, successive cuttings are thus laid side by side, forming narrow ridges; F is an additional coulter called the “skim-coulter,” for removing the surface of the earth, and is only occasionally used. There are a great many kinds of ploughs, each suitable to the kind of soil to be ploughed, whether light and dry or heavy and moist. HARROWS. Illustration: HARROW. These instruments are used to stir up, pulverise, and mix together the earth, also to tear up any roots that may be left after ploughing, and to cover up the seed after sowing. The cut represents the usual form of harrow, having a number of iron spikes or teeth attached to frames of which two or more are united together by chains and attached to a bar, that the horses may drag them over the surface of the soil. Bush-harrows consist of a bundle of brush-wood held together by a pair of frames, and drawn over the soil when it is very dry and light; they are used chiefly to cover up the seed after “drilling.” ROLLERS. Illustration: (‡ UNDULATED ROLLERS.) In clay and other heavy soils, it is necessary after ploughing to break up the large pieces by means of rollers, and in light soils to press it together; for these purposes rollers are used, either with smooth or undulated surfaces, as in the figure; these last form furrows into which the seed falls, causing it to come up in rows. Rollers of a lighter kind are used after mowing to level the surface. MOWING MACHINES. Illustration: FIG. 1. (‡ SCYTHE.) Illustration: FIG. 2. (‡ DRAY MOWING MACHINE.)