nd made not
exceeding three to four strokes per minute, the piston moving about
fifty feet per minute. To-day, steam marine engines on one and one-third
pounds of coal per horse-power--the monster ships using less--make
from seventy to ninety revolutions per minute. "Destroyers" reach 400
per minute. Small steam engines, it is stated, have attained 600
revolutions per minute. The piston to-day is supposed to travel
moderately when at 1,000 feet per minute, in a cylinder three feet long.
This gives 166 revolutions per minute. With coal under the boilers
costing one dollar per net ton, from say five pounds of coal for one
cent there is one horse-power for three hours, or a day and a night of
continuous running for eight cents.

Countless millions of men and of horses would be useless for the work of
the steam-engine, for the seemingly miraculous quality steam possesses,
that permits concentration, is as requisite as its expansive powers. One
hundred thousand horse-power, or several hundred thousand horse-power,
is placed under one roof and directed to the task required. Sixty-four
thousand horse-power is concentrated in the hold of the great steamships
now building. All this stupendous force is evolved, concentrated and
regulated by science from the most unpromising of substances, cold
water. Nothing man has discovered or imagined is to be named with the
steam engine. It has no fellow. Franklin capturing the lightning, Morse
annihilating space with the telegraph, Bell transmitting speech through
the air by the telephone, are not less mysterious--being more ethereal,
perhaps in one sense they are even more so--still, the labor of the
world performed by heating cold water places Watt and his steam engine
in a class apart by itself. Many are the inventions for applying power;
his creates the power it applies.

Whether the steam engine has reached its climax, and gas, oil, or other
agents are to be used extensively for power, in the near future, is a
question now debated in scientific circles. Much progress has been made
in using these substitutes, and more is probable, as one obstacle after
another is overcome. Gas especially is coming forward, and oil is freely
used. For reasons before stated, it seems to the writer that, where coal
is plentiful, the day is distant when steam will not continue to be the
principal source of power. It will be a world surpriser that beats one
horse-power developed by one pound of coal. The po