This operation, performed in the garden by means of the spade, is carried on in the field on a larger scale by the plough,' which breaks the soil and by inverting the furrow-slice, exposes fresh surfaces to the disintegrating influence of air, rain and frost.
As these waste places have been gradually brought under the plough, in England and Scotland particularly, the haunts and means of subsistence of the linnet have been curtailed, and hence its numbers have undergone a very visible diminution throughout Great Britain.
The "sulky" or riding plough is little known in the United Kingdom, but on the larger arable tracts of other countries where quick work is essential and the character of the surface permits, it is in general use.
Subsequently the digging plough came into vogue; the share being wider, a wider furrow is cut, while the slice is inverted by a short concave mould-board with a sharp turn which at the same time breaks up and pulverizes the soil after the fashion of a spade.
The weight of these implements necessitates some provision for turning them at the headlands, and this is supplied either by a bowl wheel, enabling the plough to be turned on one side, or by a pair of wheels cranked so that they can be raised by a lever when the plough is working.
By feeding the sheep, the land is dunged as if it had been folded; and those turnips, though few or none be carried off for human use, are a very excellent improvement, nay, some reckon it so, though they only plough the turnips in without feeding."
In the disk plough, which is built both as a riding and a walking plough, the essential feature is the substitution of a concavo convex disk, pivoted on the plough beam, for the mould-board and share of the ordinary plough.