MECHAMlAL DlVlSK^ OF SOILS. 83 



lion at the ends by a thick washer. The larger the roller 

 the greater surface is brought into contact with the ground 

 the more level it leaves it, besides giving a much easier 

 draught to the team. To accomplish this without too much 

 increase of weight, they are frequently constructed with 

 heads at the ends and closely covered like a drum. For 

 dividing compact clay lumps or for scarifying meadows, 

 they are sometimes made with large numbers of short, stout 

 angular teeth, which penetrate and crush the clods, and tear 

 up and loosen the old turf and moss of meadows. 



THE CULTIVATOR 



Has a light frame in the form of a triangular or wedge- 

 harrow with handles behind like those of a plow, and with 

 several small iron teeth in the frame, somewhat resembling 

 a double share plow. They are of various sizes, slightly 

 differing in construction, and are of great utility in stirring 

 the surface of the ground and destroying weeds. 



THE DRILL BARROW 



Is useful for dibbling in seeds, and when ihe surface is 

 mellow it will open the furrows for the reception of the 

 seed, and drop, cover and roll the earth firmly over it. The 

 smaller ones are trundled along like a wheelbarrow, by hand; 

 and the larger for field planting, having several fixtures for 

 drilling, are drawn by a horse. They are suited to the 

 smaller seeds, and some have been made to plant corn, 

 beans and peas successfully. 



SURFACE OR SHOVEL PLOWS. 



These are a cheap, light instrument, much used in Eng- 

 land, and to some extent in this country, for paring the 

 stubble and grass roots on the surfaces of old meadows. 

 These are raked together into heaps, and with whatever 

 addition there may be of earth or clay are burnt, and the 

 ashes and roasted earth scattered over e soil. There is 

 an apparent objection to this practice in the expulsion of 

 the carbon and nitrogen stored up in the plants and in the 

 waste of the coarse material of the decaying vegetables 

 which is so useful in effecting the salutary mechanical divi- 

 sions of clay soils. But by a reference to what has been 

 said on the efficiency of burnt clay or broken brick, their 

 grent utility as fertilizers will be seen. This and the ash 

 of the plants remain, and both are useful in quickening the 



