318 DRY-FARMING 
years ago, which gives the farmer full control over 
the process of seeding, is the only system to be used. 
The numerous seed drills on the market all employ 
the same principles. Their variations are few and 
simple. In all seed drills the seed is forced into tubes 
so placed as to enable the seed to fall into the fur- 
rows in the ground. The drills themselves are distin- 
Fic. 84. Disk drill and seeder. 
guished almost wholly by the type of the furrow 
opener and the covering devices which are used. The 
seed furrow is opened either by a small hoe or a 
so-called shoe or disk. At the present time it appears 
that the single disk is the coming method of opening 
the seed furrow and that the other methods will 
gradually disappear. As the seed is dropped into 
the furrow thus made it is covered by some device at 
the rear of the machine. One of the oldest methods 
as well as one of the most satisfactory is a series of 
