48 PHYSICAL CONSERVATION AND RESTORATION. 
Importance of Physical Conservation and Restoration. 
Comparatively short as is the period through which the colo- 
nization of foreign lands by European emigrants extends, 
great and, it is to be feared, sometimes irreparable injury has 
already been done in the various processes by which man seeks 
to subjugate the virgin earth; and many provinces, first trod- 
den by the homo sapiens Lurope within the last two centuries, 
begin to show signs of that melancholy dilapidation which is 
now driving so many of the peasantry of Europe from their 
native hearths. It is evidently a matter of great moment, not 
only to the population of the states where these symptoms are 
manifesting themselves, but to the general interests of hnuman- 
ity, that this decay should be arrested, and that the future ope- 
rations of rural husbandry and of forest industry, in districts 
yet remaining substantially in their native condition, should be 
so conducted as to prevent the widespread mischiefs which have 
been elsewhere produced by thoughtless or wanton destruction 
of the natural safeguards of the soil. This can be done only 
by the diffusion of knowledge on this subject among the classes 
that, in earlier days, subdued and tilled ground in which they 
had no vested rights, but who, in our time, own their woods, 
their pastures, and their ploughlands as a perpetual possession 
for them and theirs, and have, therefore, a strong interest in the 
protection of their domain against deterioration. 
Physical Restoration. 
Many circumstances conspire to invest with great present 
interest the questions: how far man can permanently modify 
and ameliorate those physical conditions of terrestrial surface 
and climate on which his material welfare depends; how far 
he can compensate, arrest, or retard the deterioration which 
many of his agricultural and industrial processes tend to pro- 
duce; and how far he can restore fertilitv and salubrity to soils 
