TILLAGE MACHINERY 



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Certain advantages over the plain smooth rollers are 

 claimed for the corrugated or tubular rollers, several 

 styles of which have been invented. They are said to 



FIG. 60 A TUBULAR ROLLER 



crush the clods better, and they do not leave a smooth 

 surface. Figs. 60 and 61 illustrate two rollers of this 



FIG. 6l A FLEXIBLE ROLLER AND CLOD CRUSHER OF SPECIAL DESIGN 



type. H. W. Campbell invented a tool of this nature 

 called the subsurface packer, for packing the ground be- 

 neath the surface. This tool (illustrated in Fig. 62) con- 

 sists of a series of wheels with wedge-shaped tread. 



