166 WHEAT 



which are driven by a small revolving shaft con- 

 nected with the main shaft by sprocket gears or 

 chains. The rate of seeding is regulated by in- 

 creasing or decreasing the width of the opening 

 through which the grain is forced or by changing 

 the speed of the grain pinions by a gear adjust- 

 ment. 



The modern force feed drill does its work very 

 accurately, and a good drill may be adjusted and 

 set to sow very evenly a definite amount of grain 

 per acre. 



THREE FORMS OF GRAIN DRILLS 



The modern wheat drill is made in three general 

 forms: 1. Hoe drills. 2. Shoe drills. 3. Disk 

 drills. Disk drills are divided into two general 

 classes: Single disk drills and double disk drills. 

 The shoe and disk drills may have press wheels 

 attached in the rear to cover and press the soil 

 over the seed, or more commonly short chains 

 are used which drag the loose earth into the fur- 

 rows and thus cover the seed. 



The hoe drills, which were the first type manu- 

 factured, open the furrow with a shovel or point 

 which is dragged through the soil and forced down 

 by pressure springs. These drills give heavy draft 

 and tend to gather trash and clog. 



The shoe drill is an advantage over the hoe 

 drill in that the shovel is replaced by a sharpened 

 runner or shoe which cuts into the soil, opening a 

 V shaped furrow. The shoe drill runs lighter 

 and tends to draw over the rubbish to some extent 

 and does not gather trash as badly as the hoe 



