xr TILLAGE OPERATIONS 77 



used to drag the weeds out of the earth when they have been 

 loosened by the ploughs and cultivators. 



The Roller, as its name implies, is used to smooth the 

 earth by being rolled over it. One heavy kind, called some- 

 times a CLOD CRUSHER, has strong projecting teeth so that 

 it easily crushes up the clods of earth it is drawn over. The 

 lighter kinds of rollers are used to press seeds into the earth, 

 and to prevent too much evaporation from the soil by making 

 the upper part more compact. 



