Steam, Its Generation and Use | Page 3

work on its down stroke
under pressure of the atmosphere. After hearing of Savery's engine,
Papin developed an improved form. Papin's engine of 1705 consisted of
a displacement chamber in which a floating diaphragm or piston on top
of the water kept the steam and water from direct contact. The water
delivered by the downward movement of the piston under pressure, to a
closed tank, flowed in a continuous stream against the vanes of a water
wheel. When the steam in the displacement chamber had expanded, it
was exhausted to the atmosphere through a valve instead of being
condensed. The engine was, in fact, a non-condensing, single action
steam pump with the steam and pump cylinders in one. A curious
feature of this engine was a heater placed in the diaphragm. This was a
mass of heated metal for the purpose of keeping the steam dry or
preventing condensation during expansion. This device might be called
the first superheater.
Among the various inventions attributed to Papin was a boiler with an
internal fire box, the earliest record of such construction.
While Papin had neglected his earlier suggestion of a steam and piston
engine to work on Savery's ideas, Thomas Newcomen, with his
assistant, John Cawley, put into practical form Papin's suggestion of
1690. Steam admitted from the boiler to a cylinder raised a piston by its
expansion, assisted by a counter-weight on the other end of a beam
actuated by the piston. The steam valve was then shut and the steam
condensed by a jet of cold water. The piston was then forced downward
by atmospheric pressure and did work on the pump. The condensed
water in the cylinder was expelled through an escapement valve by the
next entry of steam. This engine used steam having pressure but little,

if any, above that of the atmosphere.
[Illustration: Two Units of 8128 Horse Power of Babcock & Wilcox
Boilers and Superheaters at the Fisk Street Station of the
Commonwealth Edison Co., Chicago, Ill., 50,400 Horse Power being
Installed in this Station. The Commonwealth Edison Co. Operates in its
Various Stations a Total of 86,000 Horse Power of Babcock & Wilcox
Boilers, all Fitted with Babcock & Wilcox Superheaters and Equipped
with Babcock & Wilcox Chain Grate Stokers]
In 1711, this engine was introduced into mines for pumping purposes.
Whether its action was originally automatic or whether dependent upon
the hand operation of the valves is a question of doubt. The story
commonly believed is that a boy, Humphrey Potter, in 1713, whose
duty it was to open and shut such valves of an engine he attended, by
suitable cords and catches attached to the beam, caused the engine to
automatically manipulate these valves. This device was simplified in
1718 by Henry Beighton, who suspended from the bottom, a rod called
the plug-tree, which actuated the valve by tappets. By 1725, this engine
was in common use in the collieries and was changed but little for a
matter of sixty or seventy years. Compared with Savery's engine, from
the aspect of a pumping engine, Newcomen's was a distinct advance, in
that the pressure in the pumps was in no manner dependent upon the
steam pressure. In common with Savery's engine, the losses from the
alternate heating and cooling of the steam cylinder were enormous.
Though obviously this engine might have been modified to serve many
purposes, its use seems to have been limited almost entirely to the
pumping of water.
The rivalry between Savery and Papin appears to have stimulated
attention to the question of fuel saving. Dr. John Allen, in 1730, called
attention to the fact that owing to the short length of time of the contact
between the gases and the heating surfaces of the boiler, nearly half of
the heat of the fire was lost. With a view to overcoming this loss at
least partially, he used an internal furnace with a smoke flue winding
through the water in the form of a worm in a still. In order that the
length of passage of the gases might not act as a damper on the fire, Dr.

Allen recommended the use of a pair of bellows for forcing the
sluggish vapor through the flue. This is probably the first suggested use
of forced draft. In forming an estimate of the quantity of fuel lost up the
stack, Dr. Allen probably made the first boiler test.
Toward the end of the period of use of Newcomen's atmospheric
engine, John Smeaton, who, about 1770, built and installed a number of
large engines of this type, greatly improved the design in its mechanical
details.
[Illustration: Erie County Electric Co., Erie, Pa., Operating 3082 Horse
Power of Babcock & Wilcox Boilers and Superheaters, Equipped with
Babcock & Wilcox Chain Grate Stokers]
The improvement in boiler