236 AGRICULTURAL ENGINEERING 



there is no necessity of crossing the wire with the team. 

 Some friction device must be used to drive the reel. 



The double marker, or a separate marker for each side 

 and which may be raised to a vertical position when not in 

 use, is undoubtedly the most convenient marker. There 

 is less time consumed in putting it in use and there is no 

 crossing of the lines with the draw rope. Where the soil is 

 hard the disk marker should be used in preference to the 

 drag head marker. 



Adjustment. In addition to a selection of the proper 

 seed plate, or calibration of the planter, as it is sometimes 

 called, the machine should be kept in proper adjustment and 

 good working condition when in the field. One of the more 

 usual neglects of this kind is the failure to keep the planter 

 "front," the part of frame which supports the runners, 

 level. If the front be tipped back or forward, the corn will 

 be deposited in hills back or ahead of its proper location and 

 will not form perfect rows crosswise. 



QUESTIONS 



1. What are the essentials of a good corn planter? 



2. What is the difference between the "full hill" and the accumula- 

 tive drop? 



3. Why is it important to have graded seed? 



4. What is the variable drop? 



5. Describe the various styles of furrow-openers used on corn 

 planters, and give their merits. 



6. What types of wheels are used? 



7. What are some of the conveniences used on modern planters? 



8. How should planters be adjusted for accurate check-rowing? 



