152 mecha:nics. 



purposes. On light soils, it is most valuable, and may be 

 used at nearly all times with safety. Heavy or clay soils 

 will be crusted and injured if rolled while wet. The 



Fig. 1G3. 



Fkld Roller. 



roller was formerly made of a single i^iece, or of a log of 

 w^ood dressed to a true cylinder ; but this scraped the 

 earth when turned to the right or left. A great improve- 

 ment was made by cutting the single roller into two 

 parts; and a still greater, by employing cast-iron, in sev- 

 eral sections, as shown in fig. 163. The cost of cast 

 rollers is about $85 to $100. 



CHAPTER XL 

 PLANTING AND SOWING-MACHINES. 



Sowing-machines, for wheat and other grains, possess 

 great advantages over hand-sowing. All the seed being 

 deposited by them at a nearly uniform depth, and com- 

 pletely covered with earth, it vegetates and grows evenly, 

 and tlie plants are uniformly strong and vigorous. A 

 less quantity of seed is required, and the crop is heavier. 



WHEAT DRILLS. 



Several excellent grain drills are now manufactured and 

 sold in this country, having much similarity in external 

 appeai'ance. One of the best and most widely known 



