24 



GENERAL CONSIDERATIONS 



run over the ground after the seed is planted, and, 

 in the case of corn and some other crops, even after 

 the plants are up, and it thus serves to give an effi- 

 cient and very cheap first cultivation. 



The acme harrow consists of gangs of narrow, 

 knifelike, curved steel blades, arranged with their 

 cutting edges downward and adjusted to cut deeper 

 or shallower by means of levers. This is a riding 

 harrow. It does much the same work as the smooth- 

 ing harrow, but it stirs and levels the surface of the 

 soil rather more effectively. It cannot be used after 

 the crop is up. 



The spring-tooth harrow has teeth made of long 

 coiled bands of tempered steel, so arranged that the 



Spring-tooth Harrow. 



free ends dig into the soil like little shovels. Their 

 jerky, springy motion enables them to enter the 

 ground easily, and they are very effective in fining 

 it and tearing it to pieces. They are especially use- 



