Ch. I.] SMALL'S PLOUGH. ^ 



those degrees are placed from eacli otker ; tlie divisions being large towards 

 the point of the sock, but becoming gradually closer until No. 90, where it 

 is understood the furrow has gotten perpendicular, after which the curve is 

 regularly diminished. As the twist is regulated by a common level, the 

 blade must stand at an angle of 110 degrees from the square of the stock, 

 when applied to the sole of the mould-board, as at T U." Me shall not stop 

 to inquire whether this is upon true mathematical principles, for mould- 

 boards must be made of different sizes and construction, to suit the nature of 

 the land on which the plough is to be worked. The great difficulty in the 

 construction of a plough is that of adapting it to all soils, in all seasons, 

 and to all depths. If the soil break up in whole furrow, every inch of depth 

 requires, in strictness, a separate plough, or a separate mode of regulation ; 

 and this curve in the mould-board, admitting of no such regulation, forms a 

 serious objection to its use. If the semi-arch, or hollow of the hind-part 

 of the mould-board be raised sufficiently high to turn a thick furrow com- 

 pletely, it is of little use in turning a thin one; on the contrary, if it be 

 brought down sufficiently low to turn a shallow one properly, it is impos- 

 sible to turn a deep one with it in a workmanlike manner*: tlius one that is 

 calculated for ploughing a free and loose soil, and for working a fallow 

 completely, is by no means adapted for making neat work on lea land, or 

 in a clay soil. Every farmer should therefore have two sorts of ploughs 

 — one for fallow, and another for seed- furrow work ; or should have two 

 mould-boards fitted for the plough, which may be changed at pleasure by 

 the ploughman, if it be made of iron. Those, however, whose pursuits and 

 wishes for information may lead them to further inquiry upon the subject, 

 we refer to the ingenious treatise of Mr. Bailey of Chillingham — which may 

 be found in the Northumberland Report — as well as to the writings of 

 Messrs, Moore, Arbuthnot, Brown of Markle, Williamson, Finlayson, and 

 Professor Low f- 



Previously to Small's time, it seemed, indeed, as if men of science were 

 cither insensible to the defects of the ploughs then in use, or imagined 

 that they were incapable of being formed upon more correct principles ; 

 for their construction was generally left to ignorant mechanics, who were 

 not alone unskilled in any calculation of their powers, but also interested by 

 their prejudices in opposing all innovation upon that which they had been 

 previously taught. However rude the operation may be, it yet requires 

 very considerable judgment in its execution ; and the implement is one 

 which, though apparently simple, is still so complex in its powers of appli- 

 cation to the soil, that it affords ample scope to the ingenuity of the most 

 learned mathematician. The art of its construction is indeed only to be 

 attained by experience ; for the difficulty of fixing its principles, and re- 

 ducing them to such a regular theory as may suit all cases, appears insur- 

 mountable. Like every other operation in tillage, the instrument, as well as 

 the process of its use, must vary according to circumstances, as no plough 

 has yet been, nor probably ever will be constructed, superior to all others 

 in every season, and on every variety of soil and situation. Although the 

 principles of construction may be the same, yet the form must be partially 



* See Mari-hall's Rural Economy of Yorkshire, vol. 1., p. 258. 



■j- An improvement of the mould-board lias been also sutrgested by Mr. Jefferson, for- 

 merly President of the United States of America, and formed upon the idea, that, as the 

 bottom cut of the furrow is, or ought to be, perfectly flat, the breast, which comes in 

 direct contact with it, shoidd be flat also. On trial by the Board of Agriculture, it was 

 however found liable to this objection — that from the concavity, or flatness in the fore-part 

 of the breast, the loose earth of the furrow was apt to rest upnu it. — Essex Hep., vol. i., p. 138. 



