166 POWER AND THE PLOW 



factories or even an occasional old-time plowwright. Plows 

 with wooden moldboards are still made in various parts of 

 the South. 



The designer, before referred to, says that it is a curious 

 thing in plow adaptation that where one shape will work ad- 

 mirably one season it will not work at all the next year under 

 apparently the same conditions. There will be a vast difference 

 in scouring, with nothing to account for it except that the action 

 of the winter may produce physical and chemical changes in 

 the soil to affect the efficiency of the plow. 



