Steam Steel and Electricity | Page 7

the
patent on the latter expired. The steam-engine marks the beginning of a
long series of troubles in the claims of patentees.
In 1782 came Watt's last steam invention, an engine that used steam
expansively. This was an immense stride. He was also at the same time
the inventor of the "throttle," or choke valve, by which he regulated the
supply of steam to the piston. It seems a strange thing that up to this
time, about 1767, an engine in actual use was started by getting up
steam enough to make it go, and waiting for it to begin, and stopped by
putting out the fire.
Then he invented the "governor," a contrivance that has scarcely
changed in form, and not at all in action, since it was first used, and is
one of the few instances of a machine perfect in the beginning. Two
balls hang on two rods on each side of an upright shaft, to which the
rods are hinged. The shaft is rotated by the engine, and the faster it
turns the more the two balls stand out from it. The slower it turns the
more they hang down toward it. Any one can illustrate this by whirling
in his hands a half-open umbrella. There is a connection between the
movement of these balls and the throttle; as they swing out more they
close it, as they fall closer to the shaft they open it. The engine will
therefore regulate its own speed with reference to the work it has to do
from moment to moment.
[Illustration: THE GOVERNOR.]
Through all these changes the original idea remained of a vacuum at
the end of every stroke, of indispensable assistance from atmospheric
pressure, of a careful use of the direct expansive power of steam, and of
the avoidance of the high pressures and the actual power of which
steam is now known to be safely capable. [Footnote: In a reputable
school "philosophy" printed in 1880, thus: "In some engines"
(describing the modern high-pressure engine, universal in most land
service) "the apparatus for condensing steam alternately above and
below the piston is dispensed with, and the steam, after it has moved
the piston from one end of the cylinder to the other, is allowed to

escape, by the opening of a valve, directly into the air. To accomplish
this it is evident that the steam must have an elastic force greater than
the pressure of the air, _or it could not expand and drive out the waste
steam on the other side of the piston, in opposition to the pressure of
the air_." According to this teaching, which the young student is
expected to understand and to entirely believe, a pressure of steam of,
say eighty to a hundred and twenty pounds to the inch on one side of
the piston is accompanied by an absolute vacuum there, which permits
the pressure of the outside air to exert itself against the opposite side of
the piston through the open port at the other end of the cylinder. That is,
a state of things which would exist if the steam behind the piston _were
suddenly condensed_, exists anyway. If it be true the facts should be
more generally known; if not, most of the school "philosophies" need
reviewing.] Then an almost unknown American came upon the scene.
In English hands the story at once passes from this point to the
experiments of Trevethick and George Stevenson with steam as applied
to railway locomotion. But as Watt left it and Trevethick found it, the
steam engine could never have been applied to locomotion. It was slow,
ponderous, complicated and scientific, worked at low pressures, and
Watt and his contemporaries would have run away in affright from the
innovation that came in between them and the first attempts of the
pioneers of the locomotive. This innovation was that of Evans, the
American, of whom further presently.
The first steam-engine ever built in the United States was probably of
the Watt pattern, in 1773. In 1776, the year of beginning for ourselves,
there were only two engines of any kind in the colonies; one at Passaic,
N. J., the other at Philadelphia. We were full of the idea of the
independence we had won soon afterwards, but in material respects we
had all before us.
In 1787, Oliver Evans introduced improvements in grain mills, and was
generally efficient as one of the beginners in the field of American
invention. Soon afterwards he is known to have made a steam-engine
which was the first high-pressure double-acting engine ever made. The
engine that used steam at each end of the cylinder with a vacuum and a
condenser, was in this first instance, so far as any record can be found,

supplanted by the engine of