12 TREES AND TREE-PLANTING. 
At a depth of some twenty feet from the surface of 
the earth white sand is struck in both Kansas and Ne- 
braska, which is full of water, and in some places forms 
subterranean streams. This makes both these states 
famous forest-growing regions, as the roots of the trees 
readily seek the moist white sand, and the trees grow 
with a rapidity which is perfectly astonishing. 
I think the great currents of air which leave the Pa- 
cific coast humid and warm are forced up by the high 
mountains until they become cold, and are discharged 
in snows in the Rocky Mountains, when, leaving the 
mountains dry, they sweep over the great plains, find- 
ing no moisture to take up until they cross the Missouri 
and Mississippi, when, having been recharged, they 
empty in Iowa, Illinois, and Wisconsin. We know that 
in Wyoming Territory the dearth is almost complete, 
and the dry winds blow incessantly. But in Nebraska 
the heavily timbered heads of her streams give some 
humidity, and the clouds empty in frequent showers 
along the Loups, Niobrara, Plattes, Elkhorn, and Mis- 
souri. In time, as Nebraska increases her forests, the 
rains will become more frequent, and some day, should 
she persist in her present system of tree-planting, she will 
be as well watered as Iowa, Llinois, Wisconsin, or states 
farther east. 
Every one has noticed the moisture of the soil in a 
wood. There is as much difference between the soil 
under trees and that on a barren hill-top as there is in the 
temperature of a well and an open plain. The humidity 
of a forest is due to the discharge of moisture through 
the leaves of the trees. It is this peculiarity which 
keeps a stream strong and full where it flows for a long 
distance through woods; not only do the trees shade 
the stream from the rays of the sun and prevent evapo- 
ration, but they keep its banks moist and soft, and, in- 
stead of drinking up the stream, frequently contribute 
to its waters. The Elbe has lost eighteen per cent. of 
