PLOWS FOR ANIMAL POWER 165 



of furrow. The plow is made easier to guide in hard ground, 

 with more even plowing as a result. 



The plow bottom is composed of the moldboard, share, brace, 

 frog, and landside. Stubble and breaker bottoms are usually 

 made interchangeable, so that on sulky and gang plows the 

 same frame may be used for different purposes. Riding plows 

 have usually three wheels, the larger of which runs upon the 

 unplowed ground. There are two wheels with inclined axles, 

 one running in the old and one in the new furrow. These take 

 the place of the landside in guiding the plow. The plow beam 

 is attached to the frame by means of bails, and suitable levers 

 are provided to adjust the depth of plowing. The width is 

 adjusted by a lever which changes the direction of the furrow 

 wheels. Nearly all sulky and gang plows are provided with 

 frames and nearly all have tongues by means of which the 

 plow can be steered and backed. 



Gang plows are simply combinations of sulky plows, al- 

 though the sulky plow usually has a wider bottom than the 

 gang. Sixteen inches for the sulky plow and fourteen inches for 

 the gang are the most common, although twelve-inch and 

 eighteen-inch bottoms are to be had. The variation in plow 

 shapes has already been touched upon. The moldboard is 

 of course the most important source of variation. The short, 

 steep, sharply curving moldboard is used in the stubble plow, 

 and the low, narrow, gently curving type for the prairie breaker. 

 The intermediate plows are adapted to different soils and 

 different conditions. One experienced plow designer says 

 that with the exception of the necessary graduation from one 

 extreme to the other the minor differences in shape are due 

 almost entirely to local whims. To a large extent these dif- 

 ferences are recognized by the larger manufacturers. In many 

 sections, however, farmers persistently cling to some shape 

 which by reason of its extreme localization is not profitable 

 for the large manufacturer to dally with. This accounts for 

 the existence in many out of way places of small plow 



