SEVERAL IMPORTANT IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES
Year: 1803

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
FREEMANTLE, late of Bunhill Row, in the Parish of Saint Luke, Old Street,
but now of Hoxton, in the County of Middlesex, Watchmaker, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of Great Britain and Ireland,
bearing date at Westminster, the Seventeenth day of November, in the forty-
fourth year of His reign, give and grant unto me, the said William Freemantle,
His especial licence, that I, the said William Freemantle, during the term of
years therein mentioned, should and lawfully might use, exercise, and vend,
within England, Wales, and Town of Berwick-upon-Tweed, my Invention
of "SEVERAL IMPORTANT IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES;
in which said Letters Patent there is contained a proviso obliging me, the
said William Freemantle, by an instrument in writing under my hand and
seal, to cause a particular description of the nature of my said Invention,
and in what manner the same is, to be performed, to be inrolled in His
Majesty's High Court of Chancery within two calendar months after the date
of the said recited Letters Patent, as in and by the same, (relation being
thereunto had,) may more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Freemantle, do declare that the nature of my improvements in the
construction of steam engines are herein particularly described, that is to say :-
My first improvement consists in making the steam cylinder or cylinders
when more than one is made use of, so that the diameter of the bore shall be
about equal to the length of the stroke, by which means the friction will be

page_text: much reduced, for since the force of an engine is proportional to the contents
or capacity of the cylinder, which is as the square of the diameter multiplied
into the length, but the friction is proportional to the diameter multiplied into
the length, therefore it follows that in two cylinders of the same length, but of
different diameters, the friction will be less in the larger diameter, in proportion
to its force, than in that of the smaller diameter; and it is equally obvious
that in two cylinders of the same capacity, but of different lengths, the friction
will be least in the shortest cylinder, for the friction increases only as the
diameter, while the capacity (that is the force) increases as the square of the
diameter. And in a cylinder of this form, the steam having less surface
during its action, will suffer less condensation from without; and such a
cylinder will be less expensive than one of the common form.
Figure 1 represents a section of my cylinder, which is furnished with four
pipes or channels, which may be either cast solid with the cylinder, or be
screwed or bolted on in any of the usual methods. The channel or pipe M, N,
leads from M into the cylinder at N; O leads straight through into the
bottom of the cylinder; E, D, communicates with the boiler; and F, G, with
the condenser; each of those four channels terminate in the face of the
part P, Q, R, S, which must be made exceedingly flatt. The Figures of those
terminations are represented by Figure 2.
My universal circular valve is shewn at Figure 3, where A, B, C, D,
and E, F, G, H, represent two excavations nearly as deep as they are
wide, each occupying three eighths of the whole circle, so as to leave
the two solid parts A, C, E, F, and D, B, G, H, each one eighth of
the circle from A. There is a narrow circular channel about one fourth
of an inch deep, inclosing or surrounding the excavation E, F, G, H,
and entering A, B, C, D, again at B. The face of this valve must be
made very flatt, as it applys to the part P, Q, R, S, Figure 1. Now when
the engine is at rest, and all the passages shutt, the center of the exca-
vation A, B, C, D, will lay open the center of the hole or passage E,
Figures 1 and 2, and the centre of E, F, G, H, Figure 3, over the centre
of F, Figures 1 and 2; as E, D, Figure 1, communicates with the boiler, it
will be filled with steam, and consequently A, B, C, D, Figure 3, and the
channel which surrounds E, F, G, H, so that as long as the elastic force of
the steam exceeds the pressure of the atmosphere, no air can possibly enter
E, F, G, H, even tho' the valve should not exactly apply to every part of
P, Q, R, S, Figure 1. The engine when at work, by means of a crank or
other contrivance, causes the valve to vibrate on its axis one eighth of a circle,
or forty-five degrees each way from the situation before described; and it is

page_text: obvious that steam will be alternately admitted through the passages M and O
into the top and bottom of the cylinder, and that when steam is admitted into
the top of the cylinder, the bottom communicates with the condenser, and that
when the valve is turned so that steam is admitted to the bottom of the
cylinder, the top communicates with the condenser. Now, by turning the
valve into such a situation that the centre of the excavations are over the
centres of M and O, Figure 1 and 2, the holes E and F, Figures 1 and 2,
being wider than the solid parts of the valve A, C, E, F, and D, B, G, H, the
steam is at liberty to pass through the uncovered parts of E into both the
excavations in the valve, and through the holes M and O into the top and
bottom of the cylinder, and also into the condenser through the uncovered
parts of the hole F, by which means the engine may be blown of air previous
to its being set to work. When the single power engine is used, that is, when
the steam is made to act only against the bottom of the piston, and the top of
the cylinder is left open, the channel M, N, Figure 1, and the hole M, Figure 2,
will be omitted. By making use of two steam cylinders instead of one, the force
of the engine may be rendered so nearly equal in every part of its revolution as
to act with a much smaller fly than is commonly made use of; the pistons of
those cylinders being made to act on two arms of one crank placed at right
angles to each other. In this case the valve, &c. must be constructed as
follows:-The part, Figure 5, has six holes, and communicates with the boiler,
condenser, and the top and bottom of both cylinders, and may be placed in any
convenient situation between the cylinders. For distinction, we will call
one of the cylinders No. 1, and the other No. 2. The communications are as
follows: The hole F communicates with the boiler; the hole E, with the
condenser; A, with the top of the cylinder No. 1; B, with the top No. 2;
C, with the bottom of No. 1; and the hole D communicates with the bottom
of No. 2.
may,
Figure 5 represents the valve with its two excavations A, B, C, D, and
E, F, G, H, as in the valve, Figure 3. The excavation A, B, C, D, commu-
nicates with the groove K, L, M, part of which groove always lies over the
steam hole F, Figure 4; therefore let the valve be in what situation it
A, B, C, D, will always be filled with steam. In like manner, the exca-
vation E, F, G, H, communicates with I, which always laying over the hole E,
Figure 4, it follows that F, F, G, H, in every part of its rotation will have
communication with the condenser. This valve is not to vibrate like the other,
but to revolve on its axis, making one turn to each stroke of the engine. It
is very easy to conceive how the communications successively take place, so as
to produce the desired effect. If this valve be shifted half a revolution, with

page_text: respect to the crank, the communications will take place in such order as to
cause the engine to turn the contrary way. An engine constructed in this way
is capable of commencing its motion in any part of the revolution. I must
remark here that the steam passage F, Figure 4, may be placed in any part
of the circle most convenient, so that it corresponds with the groove K, L, M,
Figure 5. When two open top cylinders are used, the two passages A and B,
Figure 4, are to be omitted.
I
say
I next proceed to describe the principle on which my parallel motion
depends, and the method of constructing it, in order to which it will be
necessary to demonstrate the following proposition, vizt, that if one end of an
inflexible bar be compelled to move in a right line, and the middle point to
describe the arch of a circle whose centre is in that line, and whose radius is
equal to half the length of the bar, the other end of the bar will describe a
right line at right angles to the first line. Let A, B, Figure 6, be the bar;
D, B, the right line in which the end B of the bar is compelled to move;
D the centre of the circle in which the middle point C of the bar is compelled
to move; and D, C, the radius of the circle equal to A, C, equal to C, B,
the point A will describe a right line at right angles to B, D, which is
thus demonstrated: since A, C, equal D, C, the angle C, A, D, equal to
angle C, D, A, and as D, C, equal C, B, the angle D, B, C, equal the
angle B, D, C, therefore the angle C, A, D, added to the angle C, B, D, equal
the whole angle A, D, B, consequently A, D, B, is a right angle, and the locus
of the point A, a right line, which was to be demonstrated. I apply this to
the purpose of producing parallel motion in the following manner :-B, A,
Figure 7, is a bar or beam, either of wrought or cast iron, the end B of which
is forked, as may be seen in Figure 8, and is furnished with a friction wheel
which fits a notch in the piece F, which piece is fixed to a convenient part of
the frame of the engine. The sides of this notch must be parallel to each
other, and perpendicular to the axis of the cylinder. The friction wheel must
have two small flanges to prevent it from slipping out of the notch sideways,
as in Figure 8; there is another piece C, D, G, which turns on D by means of
brasses fixed to the frame of the engine. This piece is connected to the
bar B, A, at C, so that B, A, may turn about C as a centre. Those two pieces
may be connected by a pin, or otherwise, as may be most convenient. The
piston rod A, E, is connected to the bar B, A, by means of a joint at A. The
centre of the friction wheel at B, the centre of the joint at A, and the centre
of the axis D, on which the piece C, D, G, turns, must be all equally distant
from the centre C, where the two pieces are connected. Those conditions
being observed, it will follow from what has been demonstrated, that the

page_text: point A will describe a right line, and of consequence the piston rod connected
with it must move parallel. Rotatory motion is to be produced by connecting
the end A to the crank, by means of a connecting rod, in any of the usual
methods.
Figure 8 is an horizontal view of the parallel motion; the same letters
refering to the same parts as in Figure 7. The piece C, D, G, may be made
double or forked, as in Figure 8, or it may be made single, that is, it : may be
cutt off at the dotted lines X, Y, in which case there must be a bearing at K.
The part L, G, is intended to work the air pump. The cold and hot water
pumps may be wrought from any part of the parallel motion, as may be most
convenient; or a lever may project from any part of C, D, G, to effect either
of those purposes.
in
Figure 9 is a section of my condenser, which, instead of being of the usual
form, viz, a cylinder, is in the form of a parrellelepiped at H, in a pipe large
enough to admit the end of the pipe F, G, Figure 1. Q is the jet pipe which
enters the condenser in the centre, and projects a small way down into it.
The end X, Y, which is ground to fit the flat end of the pipe, is capable of
being elevated or depressed by means of a screw, or otherwise, so that the cold
water will flow out all round the pipe in a thin sheet, the thickness of which
may be regulated at pleasure by the screw. I apply the cold water to the
outside of my condenser in such a way as to cause a much greater number of
its particles to come in contact with the external surface of the condenser than
any method yet practised. This is effected by making the bottom of the
cistern come within a small distance of the condenser, as in the Figure,
where A, B, C, D, E, F, G, is a section of the cistern. The cold water enters
at K, and following the direction of, the darts, runs first under the condenser,
and filling the space E, F, G, B, passes under L and M, and over the whole
length of the side of the cistern at I, which is made lowest on that account.
The pieces L and M, which go across the cistern, are to compel the current to
run close to the upper surface of the condenser. The cistern may be made
square, as A, N, G, B, and a partition may be put in place of D and E, which
will answer the same purpose as making it of the Figure A, B, C, D, E, F, G.
The
space E, F, G, B, is intended to receive the air pump, which I make on
the principle of De La Hire, to exhaust both by the ascent and descent of the
piston, and is connected to the condenser by two pipes proceeding from the
side O, one leading to the top, and the other to the bottom of the air pump,
which is fixed to the side B, G, of the cistern, and discharges the hot water,
air, &c. through that side into a small cistern fixed to the outside of B, G. I
have simplified the double air pump as follows:-

page_text: Figure 10 represents a double air pump with two valves only. A, B, C. D, is
the barrel or cylinder, which in length exceeds the length of the stroke by the
length of the piston. Exactly in the middle of the barrel is a grating I, K,
communicating by means of a pipe with the condenser. E, F, G, H, is the
piston, which must be of such a length E, H, as, with the breadth of the
grateing I, K, to be equal to the length of the stroke, so that the piston at its
greatest altitude and depression shall leave the grateing uncovered. At the
top and bottom of the barrel are two valves opening outwards, which are all
that are required, the piston performing the office of the other two.
Figure 11 will explain my improvement in the cold-water pump, which
will obviate the inconveniences arising from the inertia of the ascending column
of water, and also prove of very considerable utility when the pipes leading to
the pump barrel are too small, or when the motion of the piston in the barrel
is very quick. This improvement consists in placing an air vessel so as to
communicate with the ascending column of water immediately below the lower
valve of the pump, as in Figure 11, where A, B, is the pump barrel; C, D, the
air vessel; A, the piston; and B, the lower valve. E is the pipe leading to the
well. Now, it's evident that before water can be raised into the barrel A, B,
a partial vacuum will be made in the air vessel C, D, and the rarity of the air
in C, D, will be proportional to the height of C, D, above the surface of the
water in the well, since the water can ascend in the barrel only with a deter-
minate velocity, and which depends on the height of the piston above the
surface of the water in the well, and also on the diameter of the pipe E. It
Day and sometimes does happen that the velocity of the piston exceeds that of
the water, and a vacuum is formed between the bottom of the piston and the
surface of the column of water. The effect of this is, that when the piston
begins to descend, it meets the ascending column of water, and a very violent
concussion is produced, which is exceedingly detrimental and destructive to the
pump, and any apparatus connected with it. The air vessel will prevent those
disagreeable effects taking place, for, instead of a vacuum being formed below
the piston, air will be exhausted from the air vessel; and as the piston
descends, the pressure of air on the surface of the water in the well not being
counterballanced, will continue to rise into the vessel till the equilibrium is
restored; and when the piston ascends again, the barrel will not only be sup-
plied by the pipe E, but also by the water in the air vessel, so that the piston
must require less force to lift it than if there was no air vessel. The same
effects will take place if the pipe E is too small. The air vessel may be made
in a variety of forms; perhaps that represented by Figure 12 may be as con-
venient as any, in which the air vessel surrounds the pump barrel. The same

page_text: letters refer to the same parts as in Figure 11. This improvement may be
applied either to the forcing or lifting pump.
In witness whereof, I, the said William Freemantle, have hereunto set
my hand and seal, the Sixteenth day of January, in the year of our
Lord One thousand eight hundred and four
DE IT REMEMBERED, that on the same Sixteenth day of January,
in the year above mentioned, the aforesaid William Freemantle came before
our Lord the King in His Chancery, and acknowledged the Specification
0 aforesaid, and all and every thing therein contained, in form above written.
And also the Specification aforesaid was stamped according to the tenor of
the Statute in that case made and provided.
Inrolled the same Sixteenth day of January, in the year above written.