Book IV. SWING PLOUGHS. 395 



time it is rendered more clean, and the inconvenience of the roots of the grasses or other 

 plants wliolly got rid of. It requires a strong team in the heavier sorts of soils, but this 

 is in some degree counterbalanced by the circumstance of one such ploughing being 

 mostly sufficient for the crop. It is, says a late theorist, consequently evident that, con- 

 sidering the number of ploughings generally given in the ordinary w^ay of preparing 

 lands for a crop of barley or turnips, and under the fallowing system for w^heat, and the 

 labour and expense in the latter case, in raking, picking, and burning weeds, the advan- 

 tages of this plough are probably greater than is generally supposed. It has also ad- 

 vantages in another point of view, which is, that the soil is increased in depth, and the 

 parts of it so loosened and broken down that the fibrous roots of the crops strike and 

 extend themselves more readily in it, and of course are better fed and supported. In thin 

 and sandy soils it is more particularly useful, because it cuts off all which is on the surface, 

 at the depth of an inch or an inch and a half, in order to its being laid in a state of decay, 

 for a future crop ; by which an increased depth of soil is given to every subsequent course 

 of crops, which often acts as a support, to keep up manures near the surface, as their 

 running through such soils too quickly is a disadvantage. It is also capable of being 

 made use of without a skim-coulter as a common plough. 



2614. A skim-coulter may be added to any other plough, and may be useful in turning down green crops 

 and long dung, as well as in trench ploughing. But in most instances it is thought a preferable plan, 

 where the soil is to be stirred to an unusual depth, to make two common swing-ploughs follow each other 

 in the same track ; the one before taking a shallow furrow, and the other going deeper, and throwing up 

 a new furrow upon the former. 



2615. The double share plough is distinguished by having one share fixed directly over 

 the other. It is made use of in some of the southern districts, with advantage, in putting 

 in one crop immediately after ploughing down another ; as by it a narrow shallow furrow 

 is removed from the surface, and another from below placed upon it, to such depth as 

 may be thought most proper, it being capable of acting to ten inches or more. In this 

 manner many sorts of crops, such as rye and other green crops that have much height of 

 stem, may be turned down without the inconvenience of any of the parts sticking out 

 through the seams of the furrow slices, by which the farmer has a clean surface of mould 

 for the reception of the grain. 



2616. The mining plough, or trenching plough, is sometimes employed for the purpose 

 of loosening the soil to a great depth, without bringing it up to the surface ; a mode of 

 operation which is particularly useful for various sorts of tap-rooted plants, as well as for 

 extirpating the roots of such weeds as strike deep into the ground. For these purposes 

 it may be employed in the bottom of the furrow after the common plough. It is con- 

 structed in a very strong manner, having a share but no mould-board. The share raises 

 the earth in the bottom of the furrow, and, passing on under what it has raised, leaves 

 the soil where it was found, but in a loosened state. 



2617. Somerville's double-furrow plough (Jig' 303.) is obviously advantageous in per- 



303 



forming more labour in a given time, with a certain strength of team, than other sorts of 

 ploughs, as producing two furrows at a time. It has been found useful on the lighter 

 sorts of land where the ridges are straight and wide, though some think it more confined 

 in its work than those of the single kind. The saving of the labour of one person, and 

 doing nearly double the work with but little more strength in the team, in the same time, 

 recommend it for those districts where four-horse teams are in use. This plough has 

 been brought to its present degree of perfection by Lord Somerville, especially by the 

 introduction of the moveable plates already mentioned (2607.), at the extremities of the 

 mould-board, as in His Lordship's single plough. But, as observed by an excellent 

 authority, " with all the improvements made by Lord Somerville, it can never come into 

 competition, for general purposes, with the present single-furrow ploughs." Lord S. 

 admits, that it would be no object to invade the system already established in well 

 cultivated counties ; though, where large teams are employed, with a driver besides the 

 ploughman, it would certainly be a matter of importance to use this plough, at least, on 

 lij^ht friable soils. " Their horses," he says, " will not feel the difference between their 



