4 THE TREE BOOK 



not to make gorgeous display"; the ash teaches 

 resistance ia every strong fiber : and so on. Be- 

 yond this we are not apt to go. The real uses of 

 the trees in providing shelter, food, and rai- 

 ment, and their value in the economic plan of 

 Nature are as nothing. 



For instance, how many know that if the for- 

 ests were cut down our country would soon be- 

 come a desert? The roots of the trees, extend- 

 ing deep into the earth, are constantly bringing 

 up water and discharging it into the air as mois- 

 ture. It is said that the largest steam boiler in 

 use, kept constantly boiling, could not evaporate 

 more water than one large elm would in the 

 same time. 



We have been in the habit of thinking that the 

 clouds get most of their moisture for rainfall 

 from the vast ocean. But they do not. By far 

 the better part of it is drawn up from the soil 

 through the trees and plants. Here is a little 

 experiment which you may try in proof of this : 

 Take two glasses of equal size and fill them with 

 water. Place them in the direct sunlight in the 

 open air. Into one put a few cuttings of grow- 

 ing plants with their leaves ; let the other stand 

 idle. In a few hours the water will disappear 

 from the glass containing the plants, while that 

 in the other glass will scarcely be diminished. 



