226 



AGRICULTURAL ENGINEERING 



with a closed boot, which provides a complete passageway 

 for the seed to the bottom of the furrow independent of the 



Fig. 137. A standard single-disk drill at work. This machine has 18 

 furrow-openers spaced 7 inches apart. 



disk; or with the open boot, which depends upon the disk 

 blade to supply one side of the seed tube. The closed form 

 is less likely to become clogged, but the open style provides 

 a slightly wider seed row. 



The double-disk does not have quite the penetration 

 that the single-disk has, but when the disks are quite sharp 

 this type of opener is good for cutting through trash. The 

 claim is advanced that the principal merit of the double-disk 



Fig. 138. Single-disk, double-disk, shoe, and hoe furrow-openers for 

 grain drills. The single-disk has a closed boot, or shoe. 



