LIMITS OF HUMAN POWER. 45 
Limits of Human Power. 
It is, on the one hand, rash and unphilosophical to attempt to 
set limits to the ultimate power of man over inorganic nature, 
and it is unprofitable, on the other, to speculate on what may 
be accomplished by the discovery of now unknown and unima- 
gined natural forces, or even by the invention of new arts and 
new processes. But since we have seen aerostation, the motive 
power of elastic vapors, the wonders of modern telegraphy, the 
destructive explosiveness of gunpowder, of nitro-glycerine, and 
even of a substance so harmless, unresisting, and inert as cotton, 
there is little in the way of mechanical achievement which seems 
hopelessly impossible, and it is hard to restrain the imagination 
from wandering forward a couple of generations to an epoch 
when our descendants shall have advanced as far beyond us in 
physical conquest, as we have marched beyond the trophies 
erected by our grandfathers. There are, nevertheless, in actual 
practice, limits to the efficiency of the forces which we are now 
able to bring into the field, and we must admit that, for the 
present, the agencies known to man and controlled by him are 
inadequate to the reducing of great Alpine precipices to such 
slopes as would enable them to support a vegetable clothing, 
or to the covering of large extents of denuded rock with earth, 
and planting upon them a forest growth. Yet among the 
mysteries which science is hereafter to reveal, there may be still 
undiscovered methods of accomplishing even grander wonders 
than these. Mechanical philosophers have suggested the pos- 
sibility of accumulating and treasuring up for human use some 
of the greater natural forces, which the action of the elements 
puts forth with such astonishing energy. Could we gather, 
and bind, and make subservient to our control, the power 
which a West Indian hurricane exerts through a small area in 
and described in Chapter III., post, ought to be here noticed asa splendid and 
most encouraging example of well-directed effort in the way of physical resto- 
ration. 
