On Agricidtural Mechanics. 105 



tamed that high place in the practice of good farming which they 

 now hold. 



Mr. Smith's subsoil-plough consists of the ordinary framework of a 

 plough, -without the mould-board, made strong enough to stand the 

 shocks and the strain to which an implement requiring the force of four 

 or six horses to work it must be subjected. This framework is about 



15 feet long. A sole-plate, on which a feather-shaped or pointed sock 

 shps, is attached to it by means of two uprights and a curved coulter. 

 The height of the plough, when held in a working position, from the 

 sole-plate to the beam, is about 22 inches. It is thus enabled to go 

 to a depth of 20 inches. From the furrow side of the sock a spur pro- 

 jects, over which the mass of subsoil cut by the coulter and share is 

 raised and broken, and falls down again. By the action of this spur, 

 and of the whole implement, the subsoil is effectually stirred, without 

 any of it being lifted to the surface. The effect of subsequent deep 

 ploughing, after the action of the air has thus sufficiently meliorated the 

 subsoil, will be beneficial, while without this previous cultivation it 

 would have been injurious. The subsoil-plough requires at least four 

 horses. The draught, in a rather clayey soil, was IH cvvt., going from 



16 to 18 inches deep. The draught of the common plough, which pre- 

 ceded it, and turned out the furrow in which it worked, was about 3 

 cwt. ; so that the work for the horses was about the same in either case. 

 It is found that the wider the furrow is turned out, the more efficient is 

 the operation. In a subsoil ploughing-match, held at Sterling in 1840, 

 it was found that the best work was done by that subsoil-plough which 

 was preceded by the old Scotch plough, which casts a very wide furrow. 

 It is evident that this does not necessarily imply that the subsoil-plough 

 shall pass along a fewer number of furrows in a given width of land than 

 where the furrow is narrow^er, for the width of the furrow depends not 

 on that of the furrow-slice, but on the width of the plough, which thrusts 

 the furrow-slice from the fast-land. The expense of the operation of 

 subsoil-ploughing is considerable. It varies jfrom 24-s. to 30s. per acre, 

 according to the nature of the land ; and it is evident that in rough 

 strong land, where the pickaxe is afterwards required to remove the ob- 

 structions which the plough has met with, the expense will be much 

 greater than this. This is a statement of the debit side of the farmer's 

 account of subsoil-ploughing. To find the credit side of the account, he 

 must compare his land as it was, — wet or scorched, according to the 

 weather, on which it was wholly dependent, — with his land as it now is 

 after the operation, — free and friable, dry and open; — and he must take 

 the crop he raises now, at less expense, too, than formerly ; for the land, 

 being drier, is more easily tilled ; and he must compare this crop with 

 that he used to raise on the same land. The difference will pay a very 

 great per centage on the capital he has laid out. 



Several attempts have been made to diminish the expense of 

 the operation of subsoil-ploughing. The first of them is by Mr. 

 Pusey. A description of the Charlbury subsoil-plough is given 

 in the 4th part of the 1st vol. of the ' Journal.' It combines in one 

 implement both the ploughs used in the operation of subsoiling. 



