PRACTICAL ARBORICULTURE II 
made more durable and thus avoid the waste of our present methods and per- 
mit the young trees to grow into mature timber. 
HOW SOIL IS MADE. 
The influence of trees and forest upon the soil, how they make soil by 
penetrating the clays and rocks with their roots, fertilize it with their annual 
deposit of leaves, by adding vegetable mold to sand or clay, make it produc- 
tive. Thus are agriculture and arboriculture brought into close relationship. 
RIVER NAVIGATION. 
The effects of forests in the mountain regions upon precipitation and re- 
tention of snow, and consequently the rapidity with which water flows into the 
larger streams, and the quantity of water thus borne away, has an important 
bearing upon the commerce of the larger rivers, deciding their regularity of 
flow, their flood and low water tide, and thus upon the question of eco- 
nomic transportation, which affects the citizens of other states far remote 
from the mountain forests. 
PERMANENCE OF SPRINGS. 
A great majority of springs issuing from the ground all over the valleys 
have their source of supply high in the mountains, being led by subterranean 
streams to their point of issuance, and are regulated by the same laws. 
UNDERGROUND RIVERS. 
Beneath the surface, at varying distances, from six feet in places to 100 
feet in others, along the valleys of many streams of the West, there is an 
underflow, a broad river flowing toward the oceans and gulf, from which a 
million wells are supplied, and in places the tree roots reach downward to 
gather necessary moisture, and by capillary attraction it rises to the surface 
moistening numerous agricultural crops. 
The snow upon the Rocky Mountains and other ranges melting, pene- 
trates the rocky strata, percolating through the porous masses and flowing 
between the crevices of rocks, through gravel and sand, may require years to 
reach the points from whence the water is taken, in the Dakotas, Nebraska, 
Kansas and other distant states, abundant at times, scarce in other years, so 
that a short supply of snow in the Rockies may not be felt for a decade at 
some distant point. 
Arboriculture is thus of vast importance as a national question. To 
solve the problems arising in regard to forest perpetuation a high degree of 
statesmanship will be required, men who can rise superior to the petty in- 
trigues of partisan politics and in a patriotic spirit look far into the future 
and recognize the vast requirements of the nation with its increased population 
half a century hence, see needs of agriculture, of the manufactories which will 
soon be required to import lumber from the tropics; see the demands of the 
railwavs for ties and lumber, requirements of the mines in timbers for their 
maintenance, and with still greater vision see the disastrous results of the 
present policy of forest negligence. 
This is arboriculture. 
