220 AGRICULTURAL ENGINEERING 



kind has small round disks. Each of these works much like 

 the machines after which they are patterned. They are 

 made in sizes suitable for either sulky or gang plows, and 

 are quite easy to attach. They interfere slightly with the 

 adjustments of the plow, but this matter can easily be over- 

 come. The draft of those for sulky plows will vary from 

 50 to 100 pounds, depending upon the pressure applied. 

 This means that the attachment provides about one-half 

 to two-thirds of a load for one average horse. 



LAND ROLLERS 



Types of Rollers. The plain, smooth land roller has 

 been replaced to a large extent by tubular, corrugated, or 



disk types. The change 

 has been due to some of 

 the objectionable features 

 of the work of the smooth 

 roller. It is desirable, in 

 most instances, not to 

 leave the surface of the 

 ground perfectly smooth 

 and compact. It is true 

 that for crops to be har- 



Fig. 130. A plain land roller. . -,1 ,1 



vested with the mower 



this feature is desirable, but a smooth surface usually means 

 an unnecessary loss of moisture. On a smooth surface there 

 is no soil mulch, and the 

 wind has a greater dry- 

 ing effect. 



Of the various types 

 of rollers recently placed 

 upon the market, the 

 disk roller, composed of 



