394 



SCIENCE OF AGRICULTURE. 



Part II. 



late writer advises, that in " constructing heavy rollers, the vi^orkmen should be careful 

 that they have not too great a diameter, whatever the material be of which they are form- 

 ed, as the pressure is diminished where the implement is of very large size, by its resting: 

 on too much surface at once, except an addition of weight in proportion be made. By 

 having the roller made small, when loaded to the same weight, a much greater effect will 

 be produced, and a considerable saving of expense be made in the construction of the 

 implement." And he recommends that all the larger sorts of rollers should have 

 double shafts, in order that they may be drawn by two horses abreast ; and such as are 

 employed for arable lands should have a scraper attached to them. This addition, he 

 thinks, saves much time, and prevents the driver the trouble of constantly scraping the 

 machine, especially in wet seasons, and clayey tena- 328 r 



cious lands. Strong frames are also necessary for^ '^^T"f'^ =s =:r- -^_ 



rollers, so that proper weights may be put upon them ; 

 and open boxes or carts (Jig. 328.) placed upon 

 them may sometimes be requisite, m order to contain 

 any additional weight that may be thought proper, as 

 well as to receive stones or other matters that may be picked up from the ground. Pieces 

 of wood or stone, as heavy as a man can lift, are the most suitable substances for loading 

 these implements with, where they have not the advantage of boxes" for the purpose of 

 containing such weighty substances. 



2579. The common roller is employed for the common purposes of reducing soils, and 

 for rolling wheat or other crops in the spring, and grass-seeds. It is generally about 

 five or six feet long, and from fifteen to thirty inches in diameter ; but those employed 

 for flattening one-bout ridges, in order to prepare them for drilling turnips upon, are 

 commonly shorter and of much less diameter. 



2580. The jmrted cast-iron roller was invented to remedy the inconvenience ex- 

 perienced in the use of the common implement in turning at the ends of ridges or other 

 places, where, from their not moving upon their axis, but being drawn along the surface 

 of the ground, they are liable to bear it up, and make depressions before the cylinder 

 comes again into the direct line of draught ; and at the same time they are not brought 

 round without great exertion in the teams. The cylinder, in two pieces {fig* 329.), 

 obviates this inconvenience by enabling the two parts to turn round on their own axis, 

 the one forward, and the other in a retrograde direction. 



2581. The spiky or compound roller is occasionally employed in working fallows, or 

 preparing stiflP bean land for wheat. In stiff clay-ground, when ploughed dry, or which 

 has been much trod upon, the furrow-slice will rise in large lumps, or liard clods, 

 which tlie harrow cannot break so as to cover the seed in a proper manner. In this 

 state of the ground, the rollers commonly used have little effect in breaking these hard 

 clods. Indeed, the seed is often buried in the ground, by the clods being pressed down 

 upon it by the weight of the roller. To remedy this, the spike-roller has been em- 

 ployed, and found very useful ; but a roller can be made, which, perhaps, may answer 

 the purpose better than the spike one. This roller is formed from a piece of hard 

 wood, of a cylindrical form, on which are placed several rows of sharp-pointed darts, 

 made either of forged iron, or cast metal. These darts, by striking the hard clods in a 

 sloping direction, cut or split them into small pieces j and, by this means, they roust be 

 more easily pulverised by the harrow. 



