PLOUGH. An implement drawn by horses and guided by a driver, by which the surface of the soil is cut into longi tudinal slices, and successively raised up and turned over. The object of the ope ration is to expose a new surface to the action of the air, and to render it fit for receiving the seed, or for harrowing, or for other operations of agriculture. Ploughs are of two kinds ; those without wheels, commonly called swing-ploughs, and those with one or more wheels, called wheel ploughs. The essential parts which com pose both kinds of ploughs arc, the beam by which it is drawn ; the stilts or han dles by which the ploughman guides it, being two levers connected with the beam ; the coulter fixed into the beam, by which the furrow-slice is cut ; the share, also attached to the beam, by which the slice is raised up ; and, finally, the mould-board, by which the slice is turned over. The most improved wheel-plough is the same implement, with a wheel attach ed to the beam, for the purpose of keep ing the share at a uniform distance be neath the surface, The subsoil plough, the invention of Mr. Smith, of Deanston, in Stirling, Scotland, is the swing-plough ofa somewhat stronger construction than that in common use, but without the coulter and the mould-board. The use of this implement is to follow the common plough, and loosen the subsoil at the bottom of the furrow without raising it to the sur face. The most improved form of this implement contains a muzzle (the instru ment by which it is drawn), so contrived as that the horses may walk on the firm soil. The use of the subsoil-plough is one of the greatest modern improvements that has been introduced into the culture of arable land. Draining- ploughs are of different kinds. The mole-plough, instead of a share and mould-board, has a small iron cylinder attached to the lower ex tremity of the coulter, and which, being drawn through grass land, leaves in its track a small opening, which has been compared to the underground track of a mole, and into which the water percolates from the surface through the narrow slit formed by the upper part of the coulter, and is thus carried off to an open drain.
The other kinds of draining-ploughs cut. out the soil, raise it to the surface, and turn it over in the manner of the common plow, thus leaving a deep furrow, which is commonly farther deepened and modi fied by the spade, and afterwards partial ly filled with stones, draining tiles, or other materials, through which water may find its way, and finally, covered with the surface soil. Draining-ploughs, though, in theory, promising a saving of manual labor, yet, in practice, are found inconvenient, from the number of horses required to work them. Their use is, therefore, generally confined to free, deep, loamy soils, with an even surface.
In no country is there a better test of the advancement of agriculture than in the condition of the ploughs, and the im provement in their shape. Within the tropics, but little attention is paid to the use of the plough, and in Cuba the plough used is of the rudest form : a pointed piece of iron, shaped like a wedge, attached to a wooden tongue, and drawn by a pair of oxen, without yokes; the beasts there bear the weight of their burden upon their heads (not necks), and pull by their foreheads, the rope being drawn tightly around the horns. Of course, the plough just described turns no row, but merely roots up the ground.
There are ploughs for almost every situ ation and soil, in addition to several varie ties which are exclusively used for the subsoil. Some are for heavy lands, and some for light ; some for stony, and some for land full of roots; while several are made expressly for breaking up the un filled prairies of the west. Some are fitted for deep, and some for shallow draining. There is a great economy in the use of many ploughs, and it is desira ble that every good farm should be sup plied with varieties of this useful imple ment.