horse-power, running constantly from
port to port, equal to three relays of twelve men per horse-power, is
daily exerting the power of 1,260,000 men, or 105,000 horses. Assuming
that all the steam engines in the world upon the average work double the
hours of men, then the 150,000,000 horse-power in the world, each equal
to two relays of twelve men per horse-power, exerts the power of
3,600,000,000 of men. There are only one-tenth as many male adults in
the world, estimating one in five of the population.

If we assume that all steam engines work an average of only eight hours
in the twenty-four, as men and horses do (those on duty longer hours are
not under continuous exertion), it still follows that the 150,000,000 of
effective steam-power, each doing the work of twelve men, equals the
work of 1,800,000,000 of men, or of 150,000,000 of horses.

Engel estimated that in 1880 the value of world industries dependent
upon steam was thirty-two thousand millions of dollars, and that in 1888
it had reached forty-three thousand millions of dollars. It is to-day
doubtless more than sixty thousand millions of dollars, a great increase
no doubt over 1880, but the one figure is as astounding as the other,
for both mean nothing that can be grasped.

The chief steam-using countries are America, 14,400,000 horse-power in
1888; Britain, 9,200,000 horse-power nominal. If we add the British
colonies and dependencies, 7,120,000 horse-power, the English-speaking
race had three-fifths of all the steam-power of the world.

In 1840 Britain had only 620,000 horse-power nominal; the United States
760,000; the whole world had only 1,650,000 horse-power. To-day it has
75,000,000 nominal. So rapidly has steam extended its sway over most of
the earth in less than the span of a man's life. There has never been
any development in the world's history comparable to this, nor can we
imagine that such a rapid transformation can ever come in the future.
What the future is finally to bring forth even imagination is unable to
conceive. No bounds can be set to its forthcoming possible, even
probable, wonders, but as such a revolution as steam has brought must
come from a superior force capable of displacing steam, this would
necessarily be a much longer task than steam had in occupying an
entirely new field without a rival.

The contrast between Newcomen and Watt is interesting. The Newcomen
engine consumed twenty-eight pounds of coal per horse-power a