es it, goes freely above the piston and presses it down without
meeting any obstacle; because at that same moment, the lower area of the
cylinder is in communication with the condenser. This movement once
achieved, and a certain cock having been opened, the steam from the
caldron can enter only below the piston and elevates it. The steam above
it, which had produced the descending movement, then goes to regain its
fluid state in the condenser, with which it has become, in its turn, in
free communication. The contrary arrangement of the cocks replaces all
things in their primitive state, as soon as the piston has regained its
maximum height. Thus similar effects are reproduced indefinitely.

Power is not the only element of success in industrial works. Regularity
of action is not less important; but what regularity could be expected
from a motive power engendered by fire fed by shovelfuls, and the coal
itself of various qualities; and this under the direction of a workman,
sometimes not very intelligent, almost always inattentive? The motive
steam will be more abundant, it will flow more rapidly into the
cylinder, it will make the piston work faster in proportion as the fire
is more intense. Great inequalities of movement then appear to be
inevitable. Watt's genius had to provide against this serious defect.
The throttle-valves by which the steam issues from the boiler to enter
the cylinder are constantly open. When the working of the engine
accelerates, these valves partly close; a certain volume of steam must
therefore occupy a longer time in passing through them, and the
acceleration ceases. The aperture of the valves, on the contrary,
dilates when the motion slackens. The pieces requisite for the
performance of these various changes connect the valves with the axes
which the engine sets to work, by the introduction of an apparatus, the
principle of which Watt discovered in the regulator of the sails of some
flour-mills: this he named the "governor," which is now called the
"centrifugal regulator." Its efficacy is such, that a few years ago, in
the cotton-spinning manufactory of a renowned mechanic, Mr. Lee, there
was a clock set in motion by the engine of the establishment, and it
showed no great inferiority to a common spring clock.

Watt's regulator, and an intelligent use of the revolving
principle--that is the secret, the true secret, of the astonishing
perfection of the industrial products of our epoch; this is