Every-day Science: Volume 6. The Conquest of NatureWilliams, Henry Smith
Science
Every-day Science: Volume 6. The Conquest of Nature
Williams, Henry Smith
Industrial arts; Machinery
Such an apparatus seems crude enough, yet it incorporates the essential
principles, and required but the use of ingenuity in elaborating
details of the mechanism, to make a really efficient steam engine.
It would appear, however, that Papin was chiefly interested in the
theoretical, rather than in the really practical side of the question,
and there is no evidence of his having produced a working machine of
practical power, until after such machines worked by steam had been
constructed elsewhere.
THOMAS NEWCOMEN'S IMPROVED ENGINE
As has happened so often in other fields, Englishmen were the first
to make practical use of the new ideas. In 1705 Thomas Newcomen, a
blacksmith or ironmonger, and John Cawley, a plumber and glazier,
patented their atmospheric engine, and five years later, in the year
1710, namely, Newcomen had on the market an engine which is described
in the _Report of the Department of Science and Arts of the South
Kensington Museum_, as "the first real pumping engine ever made."
The same report describes the engine as "a vertical steam cylinder
provided with a piston connected at one end of the beam, having a
pivot or bearing in the middle of its length, and at the other end of
the beam pump rods for working the pump. The cylinder was surrounded
by a second cylinder or jacket, open at the top, and cold water could
be supplied to this outer cylinder at pleasure. The single or working
cylinder could be supplied with steam when desired from a boiler below
it. There was a drain pipe from the bottom of the working cylinder,
and one from the outer cylinder. For the working of the engine steam
was admitted to the working cylinder, so as to fill it and expel all
the air, the piston then being at the top, owing to the weight of the
pump rods being sufficient to lift it; then the steam was shut off and
the drain cocks closed and cold water admitted to the outer cylinder,
so that the steam in the working cylinder condensed, and, leaving a
partial vacuum of pressure of the atmosphere, forced the piston down
and drew up the pump rods, thus making a stroke of the pump. Then the
water was drawn off from the outer cylinder and steam admitted to the
working cylinder before allowing the piston to return to the top of its
stroke, ready for the next down stroke."
It will be observed that this machine adopts the principle, with only
a change of mechanical details, of the Papin engine just described. A
later improvement made by Newcomen did away with the outer cylinder
for condensing the steam, employing instead an injection of cold water
into the working cylinder itself, thus enabling the engine to work more
quickly. It is said that the superiority of the internal condensing
arrangement was accidentally discovered through the improved working
of an engine that chanced to have an exceptionally leaky piston or
cylinder. Many engines were made on this plan and put into practical
use.
Public-domain text, read in full here on John Shaqi.
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