18 



THE OLIVER PLOW BOOK 



from below cannot reach the pulverized soil above the 

 clods any faster than the rays of light and heat evaporate 

 from above. This is plainly noticeable in the views 

 showing the water at different heights in the tubes. 



In illustration B observe that the water has traveled 

 upward in the tube to a level much higher than the 

 water in the pan, showing the force of capillary action. 

 Also observe the firmly compact condition of the earth 

 as far as the water has traveled. 



This is the way plowing is generally done. The large air spaces at 

 the bottom of the first furrow slice and the smaller one in the bottom of 

 the third are often found in fields that have been harrowed and are sup- 

 posed to be ready for planting. These air spaces interfere with the 

 upward trend of capillarity just exactly as is shown in the tubes on page 

 seventeen. 



The sectional view of plowed ground in the illustration 

 above shows very much the same condition as shown 

 in the tube. 



