21 



trees. This fact has been well put by Professor Shaler.* "In a single 

 day a tilled field may lose from its surface more soil than would be 

 taken from it in a century of its forest state." 



The above opinion is unquestionably true. The principle is, to- put 

 it in the words of Major Raymond, of the United States Engineer 

 Corps, "as well established as any other in physical science." Since 

 then it is so important, it is worth a consideration in detail. Briefly 

 the proposition may be thus stated: 



Forests by retarding the rapidity of the water flow tend, in so far, 

 to prevent the washing away of the surface soil, which is one of the 

 most important elements in agricultural prosperity. 



The expression, "pelting of the storm," is no mere figure of speech. 

 Those who have felt the weight of a falling rain-drop in an open 

 country will readily recognize that it brings with it a positively ap- 

 preciable force. If careful observation is made where the drop falls 

 on the earth, it will be noted that it has loosened the soil and made 

 a miniature excavation. The water of the fallen drop immediately 

 dissolves (at least in part) this loosened soil and begins its jo-urney 

 downward. Careful observation will also show that in an ordinary 

 uncovered space, each drop does an appreciable work if the soil is 

 at all soft. The aggregate of the fallen drops produces the inunda- 

 tion. The aggregate of the soil so removed produces the muddiness 

 of the stream, whether that be very marked, or the contrary. In 

 other words, the muddiness of the flowing water is the measure of 

 valuable, soluble soil removed from the country. It is mostly soil 

 in condition to be used in one way or another by those growing 

 plants which we denominate crops and in whose abundance we find 

 the reward of our labor.f If that soluble portion of the surface of the 

 earth were infinite, or more exactly, if the most fertile part of it,, 

 which the plants most need, were inexhaustible, we could contem- 

 plate its removal from our fields calmly. But instead of being 

 abundant, there are but few places on the earth's surface where there 

 is enough, of it to enable the farmer for any considerable period toj 

 pursue his calling without impoverishing his land, unless he take* 

 active, costly measures to restore it. The farmer does not create that 

 fertility. Whether it comes to him through the medium of his barn- 

 yard, or by purchase as an artificial fertilizer, he is simply using 

 over and again the oM elements which he has transported back to his 

 tilled acres. Hence the wisdom, the actual imperative necessity of 

 holding on to that fertility by all possible methods. This, however, 

 is not all. The increased rapidity with which water drains out of a 

 treeless country is a prolific cause of disaster, not only to those parts 



* Aspects of the Earth, p. 275. 



fThe word soluble here is used not in its chemical sense; but in the sense 

 commonly accepted i. e., the particles of soil are held suspended in the water. 



