50 PHYSICAL CONSERVATION AND RESTORATION. 
providence or malice, and abandoned by man, or occupied only 
by a nomade or thinly scattered population, the task of the 
pioneer settler is of a very different character. He is to become 
a co-worker with nature in the reconstruction of the damaged 
fabric which the negligence or the wantonness of former lodgers 
has rendered untenantable. He must aid her in reclothing the 
mountain slopes with forests and vegetable mould, thereby re- 
storing the fountains which she provided to water them; in 
checking the devastating fury of torrents, and bringing back 
the surface drainage to its primitive narrow channels; and in 
drying deadly morasses by opening the natural sluices which 
have been choked up, and cutting new canals for drawing off 
their stagnant waters. He must thus, on the one hand, create 
new reservoirs, and, on the other, remove mischievous accumula- 
tions of moisture, thereby equalizing and regulating the sources 
of atmospheric humidity and of flowing water, both which are 
so essential to all vegetable growth, and, of course, to human 
and lower animal life. 
I have remarked that the effects of human action on the forms 
of the earth’s surface could not always be distinguished from 
those resulting from geological causes, and there is also much 
uncertainty in respect to the precise influence of the clearing 
and cultivating of the ground, and of other rural operations, upon 
climate. It is disputed whether either the mean or the extremes 
of temperature, the periods of the seasons, or the amount or dis- 
tribution of precipitation and of evaporation, in any country 
whose annals are known, have undergone any change during 
the historical period. It is, indeed, as has been already obser- 
ved, impossible to doubt that many of the operations of the 
pioneer settler tend to produce great modifications in atmos- 
pheric humidity, temperature, and electricity; but we are at 
present unable to determine how far one set of effects is neutral- 
ized by another, or compensated by unknown agencies. This 
question scientific research is inadequate to solve, for want of 
the necessary data; but well conducted observation, in regions 
now first brought under the occupation of man, combined with 
