he century-plants, once
supposed to bloom only at the end of a hundred years, so history, in the
large, exhibits discoveries whose harvests are gathered only after the
lapse of aeons instead of years. The arts of fire were slowly elaborated
until man had produced the crucible and the still, through which his
labours culminated in metals purified, in acids vastly more corrosive
than those of vegetation, in glass and porcelain equally resistant to
flame and the electric wave. These were combined in an hour by Volta to
build his cell, and in that hour began a new era for human faculty and
insight.

It is commonly imagined that the progress of humanity has been at a
tolerably uniform pace. Our review of that progress will show that here
and there in its course have been _leaps_, as radically new forces have
been brought under the dominion of man. We of the electric revolution
are sharply marked off from our great-grandfathers, who looked upon the
cell of Volta as a curious toy. They, in their turn, were profoundly
differenced from the men of the seventeenth century, who had not learned
that flame could outvie the horse as a carrier, and grind wheat better
than the mill urged by the breeze. And nothing short of an abyss
stretches between these men and their remote ancestors, who had not
found a way to warm their frosted fingers or lengthen with lamp or
candle the short, dark days of winter.

Throughout the pages of this book there will be some recital of the
victories won by the fire-maker, the electrician, the photographer, and
many more in the peerage of experiment and research. Underlying the
sketch will appear the significant contrast betwixt accessions of minor
and of supreme dignity. The finding a new wood, such as that of the yew,
means better bows for the archer, stronger handles for the tool-maker;
the subjugation of a universal force such as fire, or electricity,
stands for the exaltation of power in every field of toil, for the
creation of a new earth for the worker, new heavens for the thinker. As
a corollary, we shall observe that an increasing width of gap marks off
the successive stages of human progress from each other, so that its
latest stride is much the longest and most decisive. And it will be
further evident that, while every new faculty is of age-long derivation
from older powers and ancient aptitudes, it nevertheless comes to the
birth in a moment, as it were, and puts a strain of probably fatal
sev