Some Steam Engine Prehistory

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Mr. Ball's Case Model at Blaker's Reunion in 1948. Courtesy of Ernest Hoffer, 444 Starr Ave., Toledo, Ohio 43600
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A large Geiser engine with a windlass under it for pulling a scraper to make a large fill here at Eldora forty years ago. The frame and wheels is all that remains of it now. It is at Neil Miller's Show at Alden. Courtesy of Robert Gray, R.R. 2, Eldora, Io
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F.W. Bloom's Steam Roller at Blaker's Reunion in 1948. Courtesy of Ernest Hoffer, 444 Starr Ave.. Toledo, Ohio 43600
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A Reeves C-C engine pulling eight binders in Saskatchewan, Canada about 1910-1912. I wonder how many men it would take to keep up shocking with this outfit. Hope there were no rattlesnakes when they lifted up the sheaves. Courtesy of Harry Fischback, Kett

178 Emerson Place, Brooklyn, New York 11205.

After reading the May-June issue of I.M.A. I especially enjoyed
the article, ‘My First Engine’ by George Eves. Hopefully
Mr. Eves can be persuaded to give us some more of his
experiences.

Many history books and encyclopedias have taken to copying
earlier material without checking out all the facts and have thus
been guilty of perpetrating errors. For example, how many history
books state that Robert Fulton ‘invented’ the steamboat?
Similarly Watt is commonly known as the inventor of the steam
engine when his credit should actually be an improver of an already
existing machine, for the Newcomen steam engine was at work for
over 60 years before Watt put his hand to it.

Numerous attempts were made during the late 1600’s to
harness the force of steam but almost all proved impractical.
Ironically, the man who came closest to ‘discovering’ the
principle of the steam engine did not apparently realize what he
had and didn’t follow up his experiments. This was Denys Papin
who was one of the large number of amateur scientists of the 17th
century who together did so much of the work which laid the
foundations of ‘hard science’, which was to follow.

As one of his experiments, Papin fitted a piston in a small
vertical cylinder and attached a cord to the piston which ran up
over pulleys and was attached to some weights. Water was placed
into the cylinder and a fire (probably an alcohol or similar type
lamp) placed under it. When the water boiled the resulting steam
allowed the weights to pull the piston up in the cylinder. The
source of heat was removed and when the cylinder had cooled the
steam condensed and formed a vacuum. Atmospheric pressure then
forced the piston down which, by means of the cords, pulled the
weights up. Here was the Newomen type engine in principle but Papin
saw it as nothing more than a toy and of no practical use. To add
to the irony, Papin used a type of device which had been developed
by Von Guericke about 1672 in the course of his experiments on
atmosphere pressure. The difference between the two was that Von
Guericke used an an pump to create his vacuum while papin used the
condensation of steam. Papin did not invent the piston and cylinder
concept, for not only Von Guericke, but the ancient Romans knew of
piston type water pumps. Plunger type pumps were also known at the
time of Christ, but without packing glands, which made them of
little use. It was not until Sir Samuel Morland invented the packed
Plunger pump in the late 1600’s that this type became
practical. There are some writers who do not even credit Papin with
pioneering the use of steam under a piston to develop a vacuum and
as early as 1678 experiments were being made to create a vacuum in
closed vessels by exploding gun powder. By 1698 Thomas Savery had
developed his pumping ‘ engine’, which involved creating a
vacuum by means of steam condensation and the stage was now set for
the reciprocating steam engine. Savery’s device consisted of
two closed copper chambers connected at the top to a steam supply
from a boiler and at the bottom to the water suction and discharge
lines. The attendant started the apparatus by opening a cock, or
valve, in the steam line and filling one of the chambers with
steam. The steam supply was shut off and cold water from another
line was allowed to run over the outside thus condensing the steam
inside. As a vacuum formed, atmospheric pressure forced the water
to be pumped up the suction pipe into the chamber. When the steam
cock was once again opened, steam (which at one point was reported
to be as high as 120-150 psi pressure) was admitted into the top of
the chamber forcing the water out. Check valves in the suction and
discharge lines directed the flow thru the proper lines and with
two chambers in use, one was filling while the other was
discharging. All valve operations were performed by hand. The
practical suction lift of this device was about 25′ or so and
as Savery had developed his pump for use in mines deeper than this,
he planned to install both pump and boiler in the mine itself.
Available steam pressure limited the discharge head, however, and
this device still left much to be desired, especially insofar as
economy of operation. The same theory interestingly enough was used
for ‘Pulsometer’ type sinking pumps for mine work which
remained in service until fairly recently especially in Europe. One
of Papins other developments without which steam boilers would be
rather dangerous, was the safety valve. This was of the simple
lever and weight type and here again we find that although a person
(in this case Papin) is credited with discovering an idea, he
actually took an existing concept and made it practical. Very
primitive types of safety valves consisting merely of tapered plugs
driven into a hole had been used for hundreds of years on stills
and retorts. Papin’s, however, was first of all capable of
fairly fine pressure adjustments and, secondly, was self resetting
when the steam pressure dropped below the blow off point. And on
this basis he gets and deserves credit.

Papin developed this device for use on the pressure cooker he
invented in 1680. Here again, one writer, Thomas Ewbaun, on page
393 of ‘Descriptive and Historical Account of Hydraulic and
other Machines for Raising Water’, published in 1856, quotes
several Biblical sources which he interprets as referring to a type
of pressure cooker, thus indicating that the item in question was
known previously.

To return to the steam engine, we find an interesting reference
in a diary kept by one Roger North to a device which he saw in
about 1680. His description and crude drawing includes a boiler,
two vertical cylinders, racks, pawls, ratchet wheels and
‘wheelwork’, the latter of which operated stop cocks to
control the steam flow to the cylinders. There is strong evidence
to link this engine to Sir Samuel Morland and if this be the case
he has the distinction of building the world’s first
reciprocating steam engine with self-acting valve gear.
Unfortunately, no solid evidence has come to light to prove or
disprove this point nor are any details know. And it was 1712
before the first recorded full size reciprocating engine was built.
Savery’s pumps were, however, in use draining mines by this
period but it is not known for certain if Newcomen was at first
familiar with them or not. What is known is that Newcomen and
Savery became partners due to the fact that Savery held a patent
issued in 1698 for raising water by fire, the wording of which, of
course, covers any type of engine powered by a boiler. It is
believed by some writers that a semi-experimental Newcomen engine
may have been in service as early as 1705 and it is interesting to
note that this is also the date at which Savery abandoned his
efforts on behalf of his own engine, and it is also believed to be
the date of the Savery-Newcomen partnership. It seems that we shall
never know for certain.

The Newcomen engine was of a beam type but it did not use a
slide valve. The steam admission valve was located inside the
boiler and consisted of a flat fan shaped sector plate mounted on a
stem which passed thru the boiler shell. A slight rotation of the
stem caused the plate to pass over the steam opening, like a
shutter to open or close the supply to the cylinder. Pressure were
so low, 1/2 to 1-1/2 psi, that this mechanism worked quite well.
The slide valve was unkown at this time for it (and also the
eccentric) was developed by William Murdoch, who was a foreman, and
later manager of Boulton and Watt, some time during the 1780’s.
Slide valves did not really become popular till after 1800 and many
types of pumping engines used poppet valves and plug rods similar
to those of Watts day till long after 1900.

The pistons of Newcomen engines were not pushed during the
non-condensing portion of the engine cycle for two reasons. First,
the piston was connected to the end of the beam by chains of a type
similar to today’s link-belt chains, and this arrangement would
not have transmitted any compressive force from the piston to the
beam as a solid piston rod would. The engine was so constructed
that the pump rods at the other end of the beam outweighed the
engine parts thus pulling the piston up when the vacuum was broken
by the opening of the steam valve. Secondly, the steam pressure was
so low that there was not enough ‘push’ to have done much
good and in fact the piston often pulled the steam out of the
boiler! This condition led to a series of events which eventually
came down to us as the never-to-die-out story of the boy, Humphrey
Potter, and his cords.

Newcomen’s first experimental engines were undoubtedly hand
valved but by the time they were being offered on a commercial
basis the self-acting valve gear had been developed. This consisted
of a ‘plug rod’, which was a long timber, suspended
vertically by chains from an arch head on the beam and fitted with
pins or ‘stops’ which struck the handles of the valve gear
as the beam rose and fell, thus opening or closing the appropriate
valves. Obviously, great care was needed in setting the stops for
there was nothing to prevent the piston going out of the top of the
cylinder or hitting the bottom if they were incorrectly adjusted.
In later engines spring beams were fitted so that they would be
struck by the engine beam before the piston traveled too far in
either direction.

A boy was involved in the valve gear story, as was Humphrey
Potter, but it was to properly team it a boy!

It was soon discovered that the primitive boilers then employed
could not supply steam fast enough for the engine, and of course
lack of steam meant loss of vacuum, bringing the engine to a halt.
Newcomen, therefore, regulated his engine speed by boiler pressure
so that the condensing, or power stroke, did not occur until enough
steam was available in the boiler to refill the cylinder for the
next stroke. To accomplish this, the valve gear was so arranged
that as the pump rods pulled the piston to the top of its cylinder,
the weight operated cold water injection valve was ‘cocked’
but held from being opened by a catch. A large vertical tube passed
thru the top of the boiler into the water space and a float was
fitted inside this tube and connected to the valve gear catch. As
the boiler steam pressure recovered, the water in the tube was
forced up slightly, thus raising the float which, in turn, tripped
the injection water gear. The steam in the cylinder was condensed,
the piston made its power stroke as it moved down and was again
pulled up as the steam admission valve opened and broke the vacuum.
It is important to note at this point that it was necessary for the
steam pressure, and hence the water level and float, to drop each
stroke to allow the injection gear to latch before it could be
tripped again. As boilers were made larger and better, it was
evident that under slow rates of pumping the boiler steam pressure
did not fall enough during each stroke to allow the valve gear to
function properly. Under these circumstances, the procedure was to
make the bouy inoperative by disconnecting or jamming it in its
tube. The injection valve gear was then tripped by hand as the
piston reached the top of its stroke and here we come to our old
friend, Humphrey Potter. The Potter family had been involved with
mines and Newcomen engines and so it is not surprising to find one
of its younger members, Humphrey, helping to operate an engine. It
was he who added a cord from the injection gear to the plug rod,
thus causing the engine to trip the valve and eliminating the need
for manual attention to this chore. However, his contribution was
merely an additional refinement and he in no way can be credited
with inventing the self-acting valve gear. A much modified version
of the Potter cord remained an integral part of Newcomen engines
from then onwards although engines were built for several years
with both ‘bouys’ and ‘Potter cords’ so that they
could be operated at will with either. By 1718 Henry Beighton built
a Newcomen engine and is said to have been the first to eliminate
both the cord and bouy substituting instead a linkage operated
solely by the plug rod.

Removing the bouy pipe from boilers created a new problem, that
of preventing excess pressure build up. The open topped pipe acted
as a vent, for an overpressure condition would blow some of the
water up the pipe until the steam could relieve itself to the
atmosphere. It was about 1718, therefore, that the safety valve
appeared on boilers to soon become a standard fixture. Some early
boilers were, by the way, fitted with two safety valves. They were
so weak they needed one to prevent explosions and one to prevent
the boilers from collapsing due to formation of a vacuum when they
cooled down.

Although Watt’s early engines operated at only several
pounds of steam pressure, he was not only aware of the expansive
force of steam, but was the first to use a cut off. He had thought
about doing this as early as 1769 but it was not until 1776 that
the engine driving ‘Boulton and Watts’ Works was altered to
operate expansively. There is, of course, no difference insofar as
operating an engine with a steam cut off if the engine exhausts
into a vacuum or a back pressure, other than varying the actual
point of cut off itself to compensate for the loss of power due to
the back pressure. In 1778 Watt constructed an engine for the
Shadwell Water Works in London that had adjustable pins in the plug
rod to allow a cut off at 2/3 of the stroke. Steam pressure at this
time was 10-14 psi. This expansive principle was patented in 1782
by Watt who also at about this time invented the indicator, another
device which is still being used today. It was in a much cruder
form than those with which we are familiar but its principles were
the same.

One of the main factors that contributed to the acceptance of
Watt’s engines over those of Newcomen’s was the lesser cost
of fuel, for the former were using less than half as much for a
given horse power. This was due not only to the adopting of an
early cut off but also to the separate condenser which by itself
may well rank as the most important single improvement in the
history of the steam engine.

The foregoing is of necessity a very condensed version of the
steam engine’s pre-history and many factors, as well as many
early pioneers have been skipped over.

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