CERTAIN IMPROVEMENTS IN STEALI ENGINES, SOME OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER PURPOSES
Year: 1816

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
THOMAS DAWES, of West Bromwich, in the County of Stafford, Iron Master,
send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Sixth day of February, in the fifty-sixth year of His reign, did
give and grant unto me, the said John Thomas Dawes, my exors, admors,
and assigns, His especial licence, full power, sole privilege and authority, that
I, the said John Thomas Dawes, my exors, adñiors, and assigns, during the
term of years therein expressed, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed, my
Invention of "CERTAIN IMPROVEMENTS IN STEALI ENGINES, SOME OF WHICH
IMPROVEMENTS ARE APPLICABLE TO OTHER PURPOSES;" in which Letters Patent
there is contained a proviso obliging me, the said John Thomas Dawes,
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 next
and immediately 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
John Thomas Dawes, do hereby declare that my said Invention is described
and ascertained in manner following (that is to say):-

page_text: My improvements relate to two different parts of the steam engine. First,
an improvement to supersede or answer the purposes of that part which in
common steam engines is called the parallel motion or parallel levers, and
which are usually employed with a beam or lever working upon a centre by
means of my improvement herein-after described. The alternately ascending
and descending motion of the piston rod in a right line, which I also call
reciprocating motion), is made to produce a continuous rotary or circular
motion of the fly-wheel or main shaft of the engine; or when this same
improvement is applied to other purposes, such as working pumps, saws, or
other machines which depend upon an alternate rectilinear motion, my im-
provement will be employed for the reverse object, viz to obtain such a
reciprocating motion from the continuous rotary motion of a shaft, such as that
of a water wheel or other first moving power.
Secondly, an improvement in the movement for alternately opening and
shutting the valves which admit the steam into the cylinder, and allow it to
pass away from the same to the condenser or to the open air.
The principal parts of an engine to which my first improvement is applied
are represented in Figures 1 and 2 of the Drawings hereunto annexed, upon
which I shall observe that the nature and construction of the steam engine to
which this improvement may be applied need not be herein described, as it is
no part of my Invention, but that my means of producing the rotary motion
from the rectilinear motion is applicable to any kind of steam engine what-
soever which operates with a cylinder and reciprocating piston rod with a view
of producing a continuous circular motion, provided that the parts of the
engine can be made so as to admit of the crank sbaft, or that shaft to which
the rotary motion is to be communicated, being placed so as to intersect the
line of the piston rod or centre line of the cylinder when produced at right
angles. The engine represented in the Drawing at Figure 1 and 2 is of this
description. A is the cylinder; a, the piston rod; B, the fly-wheel; C, its
axis supported in bearings D, D, so that its centre line produced cuts the
centre line of the cylinder at right angles. Upon the extremity of this shaft C
is fixed a crank S, the radius d, c, of which is equal to one fourth the stroke
or excursion of the piston rod. Therefore, the whole stroke of the crank, or
the diameter of the circle which the pin c describes, is equal to half the stroke
of the piston rod. To the pin c of the crank a bar F, m, p, which I call the
connecting bar, is jointed by the said pin c passing through the bar in the
middle of its length, so that it can turn round freely upon the pin. The con-
necting bar has at each end a pin m and p projecting perpendicularly outwards
from it, which pins are exactly at equal distances from the centre F; and also

page_text: both these distances F, m, and F, p, are exactly equal to the length or
ridicus d, c, of the crank. The pin p passes through a slider or friction wheel
fitted into a vertical groove e, e, which is formed in the fixed frame E, E, e, e,
and by this means the pin is confined to move in a vertical direction, and no
other. The pin p projects through the slider and groove E, and the upper
end of the piston rod a is jointed to it. The frame E, E, e, e, is firmly fixed
by columns H from the floor, or it may be fixed to the cylinder or any other
support. The pin m at the opposite end of the connecting bar passes through
a slider or friction wheel, which traverses horizontally in a groove E, E,
formed in the same frame E, E, e, e, so that the pin m is retained to move
backwards and forwards in a horizontal line E, which line is in the same plane
with the line of the vertical groove e, e, in which the pin p moves, and the
said lines intersect each other at right angles; and also the centre line of the
axis C of the crank (when produced) will pass through the same point of
intersection, but in a direction perpendicular to the plane in which the other
two lines are situated. The consequence of this construction is to produce
the the continuous circular motion of the crank S from the alternate rectilinear
notion of the piston rod a, because whilst the end thereof, and also the pin p
of the connecting bar is compelled to move in a vertical direction by the per-
pendicular groove e, e, the end m of the connecting bar is compelled to move
horizontally, in the horizontal groove e, e, and in consequence the centre
point F of the said bar will, in its motion describe a circle; and the crank
pin c, being attached to that point, will receive a circular motion therefrom.
The movement known by the name of sun and planet wheels may be applied
to my first improvement, and will make the fly-wheel axis revolve three times
for one revolution of the crank. For this purpose a cog-wheel must be fixed
upon the connecting bar at F, so as to turn round with it, and this is called
the planet wheel, and is to give motion to another similar cog-wheel fixed fast
upon the extremity of the axis of the fly-wheel, which axis must pass through
a hollow or tube, which is the axis of the crank, and with which the crank
revolves, but independantly of the fly-wheel, the axis of which, as before
mentioned, passes through the hollow or tube in the axis of the crank and
the aforesaid wheel, which is fixed on the end of the axis of the fly-wheel,
is situated in the front of the crank; and this latter is the centre or
sun wheel, which will be made to revolve three times for one ascent and
descent of the piston rod, provided the two wheels are of equal diameter.
The air pump of the engine may be worked by a rod T jointed to the extre-
mity of the pin p; and therefore the rod will have the same movement as
"

page_text: the piston rod, or the cylinder of the steam engine to which my improve"
ment is applied may be inverted and suspended over the crank; then the
piston rod, being prolonged, will serve to work the air pump below, or
any other method of working the air pump and other necessary pumps may
be used.
My second improvement, viz the machinery for working the valves, is
shewn in Figs. 4, 5, 6, and is also represented in Figure 2, as being applied
to the same engine as the first improvement, but it is equally applicable to
any other form of steam engine. In all these Figures, C represents the axis
of the fly-wheel, and r a tooth or leaf projecting from it. In its revolution
this alternately actuates through double levers L, P, T, and V, X, Y, each
moveable upon fixed centre pins P and X, situate on opposite sides of the
main shaft C. The levers are connected by the rods V, T, and L, Y, in con-
sequence of which any motion given to one lever will be communicated to the
other in an opposite direction. To either of the double-headed levers V, X, Y,
two rods v, y, are jointed on opposite ends V, Y, and conducted to the valves,
one rod being connected with that pair of valves which causes the piston to
ascend when they are opened, and the other rod is connected with that pair
which causes the piston to descend when they are opened. The manner of
making the connection will vary in almost every different instance, but in the
engine represented at Figure 2 in the Drawing it is evident from inspection.
The action of this mechanism is by the tooth r striking the arms a or t of the
levers as the axis C revolves in the direction of the arrow. When it strikes
the arm t of the upper lever it passes and leaves the two in the position
of Fig. 4; but when the shaft C has made half a revolution the tooth r
meets the lower lever a, as represented in Figure 6, and moves then into
the position of Figure 5, and so on alternately to change the valves at
every stroke.
I make no claim to any particular form or arrangement of the valves, my
Invention being confined to the manner of giving motion to them as above
described, and by means of which they are caused to open and shut suddenly,
and at the moment when the piston is at the top or bottom of its stroke, and
therefore nearly motionless.
In witness whereof, I have hereunto set my hand and seal, this Third
day of April, in the year of our Lord One thousand eight hundred and
JOHN THOMAS (L.S.) DAWES.

page_text: AND BE IT REMEMBERED, that on the Third day of April, in the year
of our Lord 1816, the aforesaid John Thomas Dawes came before our said
Lord the King in His Chancery, and acknowledged the Specification atore-
said, and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stampt according to the
tenor of the Statute made for that purpose.
Inrolled the Third day of April, in the year of our Lord One thousand
eight hundred and sixteen.