58 PRACTICAL FORESTRY 
wattlework or sticks woven between stakes to hold the 
soil in place until forests are started. Trees are ex- 
tensively planted along railroads, especially the locust 
and willow, to hold embankments; and the industri- 
ous Hollanders check the force of the great rivers of 
the Rhine delta by planting willows along their banks. 
The process of washing, which carries with it the 
most fertile part of the field, is strikingly visible on 
almost every hillside farm. Every stream in culti- 
vated regions is more or less discolored with mud 
which has washed from the fields. This can be pre- 
vented to a very great extent by preserving the forest 
in the proper places, especially on hilltops and steep 
slopes, and along streams. 
4. Tuer Forest as A FLroop-PREVENTER AND CoNSER- 
vator oF MorIsTURE 
In studying the causes of floods, there are many 
factors which must be considered. The first is, of 
course, the nature and amount of rainfall. The sec- 
ond factor is the steepness of the sides of the col- 
lecting-basin; the third, the nature of the soil; the 
fourth, the condition of the surface cover of the 
collecting-basin; and the fifth, the shape of the 
collecting-basin. There are still other factors, such 
as the number of waterfalls or dams, time of the 
year, ete. 
