392 



SCIENCE OF AGRICULTURE. 



Tart II. 



basis of his improvements. The swing plough has been since varied a little, in some 

 parts of Scotland, from Small's form, for the purpose of adapting it more completely to 

 particular situations and circumstances. Since 1810, this plough has been very generally 

 made entirely of iron. In Northumberland the mould-board is made less concave than 

 in Berwickshire, and in Berwickshire it is even less concave than in Small's plough. Dif- 

 ferent degrees of concavity in the mould-board suit different soils: soft and sandy soil 

 requires most, and a loamy or clayey soil least, concavity. The following are the prin- 

 cipal varieties of the improved Scotch plough at present in use in the most improved 

 districts of the north, and among scientific farmers in all countries. 



2601. Small's plough. The mould-board is more concave than in most other varieties, 

 and this may be considered its characteristic as compared with these varieties. It is 

 sometimes drawn by a chain proceeding from the muzzle to the head, in order to lessen 

 the strain on the draught-beam, and in that case it is called Small's chain plough. 

 It is commonly made of wood and iron {Jig. 294. a, as seen from the right side, 6 

 from above), but also entirely of iron. 



294 



2602. The Northumberland plough, and the Berwickshire plough, are very nearly the 

 same implement ; differing from Small's plough in having the mould-board less concave. 



2603. WWae's siving 

 plough, the best iron 295 

 swing plough in Scot- 

 land, (Jig. 295. a, as 

 seen from above, b the 

 left side) is formed en- 

 tirely of iron except the 

 points of the handles. 

 Its characteristic, in 

 point of form, is a 

 longer mould-board 

 with a greater twist in 

 it, the object of which 

 is, to reverse the fur- 

 row more completely 

 in light or highly pul- 

 verised soils. 



2604. Finlay son's iron ploughs {Jigs. 296 to 299.) are, as he informs us {British 

 Farnier, p. 9.), constructed in imitation of those of Wilkie, but with improvements and 

 modifications adapted for particular circumstances. 



2605. The heath or self-cleaning plough, or rid plough, (Jigs.296, 297.), is formed with 

 the beam so curved vertically ( fig. 296.), or divided and curved horizontally (Jig. 297.), 



as to leave no resting place for stubble, heath, or other vegetable matter, at the top of 

 the coulter, where in rough grounds, with ploughs of the ordinary construction, it gets 

 entangled and stops the work. 



2606. Finlayson's Kentish skeleton self-cleaning plough (Jig. 298.) is intended as a sub- 

 stitute for the common Kentish turn-wrest plough. " The soil, in great part of Kent, 

 is of a peculiarly adhesive clay. When this soil is between the wet and dry, it adheres 



