THE CAMPBELL SYSTEM 



in certain places ; as, for example, where 

 the soil was compacted when a horse 

 stepped over the plowed field leaving 

 the impress of its hoof -prints on land 

 which was afterwards sown to wheat ; or, 

 perchance, where the wheel of a heavy 

 farm wagon had rolled over the furrow- 

 slice, there the growth of the grain was 

 always taller, darker, healthier in color, 

 wide-leaved, giving a greater stooling 

 and larger heads. This was the first great 

 principle, namely, that the soil in the 

 lower part of the furrow had been made 

 firm and fine — in a word, compacted. 

 But Mr. Campbell also noted that wher- 

 ever the horse had lifted his foot a little 

 loose earth was left behind; just as, in 

 hke manner, the rolling of the wagon 

 wheel let fall a little loose soil. Here was 

 the second great principle, namely, the 

 formation of the "soil" or "earth-mulch." 

 Thus the purpose of the Campbell sub- 

 149 



