METHODS OF LESSENING THE CONSUMPTION OF STEAM AND FUEL IN WORKING FIRE ENGINES, AND ALSO METHODS FOR THE IMPROVEMENT OF CERTAIN INSTRUMENTS USEFUL FOR MINING OR OTHER PURPOSES
Year: 1813

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
DUNKIN, of the Town of Penzance, in the County of Cornwall, Gentleman,
send greeting.
WHEREAS King George the Third, by His Letters Patent under the Great
Seal of the United Kingdom of Great Britain and Ireland, bearing date at
Westminster, the Thirtieth day of January, in the fifty-third year of His
reign, did give and grant unto me, the said Robert Dunkin, my exors, adiñors,
and assigns, His especial licence, full power, sole privilege and authority, that
I, the said Robert Dunkin, my exors, adiñors, and assigns, during the term
of years therein expressed, should and lawfully might make, use, exercise,
and vend, within that part of the United Kingdom of Great Britain called
England, His Dominion of Wales, and Town of Berwick-upon-Tweed, and
also in all His Colonies and Plantations abroad, my Invention of "METHODS
OF LESSENING THE CONSUMPTION OF STEAM AND FUEL IN WORKING FIRE ENGINES,
AND ALSO METHODS FOR THE IMPROVEMENT OF CERTAIN INSTRUMENTS USEFUL FOR
MINING OR OTHER PURPOSES;" in which said Letters Patent there is contained
proviso that if I, the said Robert Dunkin, shall not particularly describe
and ascertain the nature of my said Invention, and in what manner the
same is to be performed, by an instrument in writing under my hand and
seal, and cause the same to be inrolled in His High Court of Chancery
within six calendar months next and inmediately after the date of the said
Letters Patent, that then the said Letters Patent, and all liberties and advan-
tages whatsoever thereby granted, shall utterly cease, determine, and become
void, as in and by the same, relation being thereunto had, doth appear.

page_text: NOW KNOW YE, that 1, the said Kobert Dunkin, do hereby declare that
my Methods of Lessening the Consumption of Steam and Fuel in Working
Fire Engines, and for the Improvement of certain Instruments useful for
Mining or other Purposes, are as follows, that is to say :-
Whereas in a steam engine of double power the steam pipe has a communi-
cation with the top and bottom of the cylinder, having a valve at each, now I
increase the capacity of that part of this pipe which is between these points in
any degree required, and alter the figure of it according to the circumstances
and situations wherein it may be applied; and I add two other valves, one on
the steam pipe towards the boiler, and the other on the top of this enlarged pipe
or vessel, between that and the usual valve at the top of the cylinder, so that
the steam from the boiler may be allowed to pass into cylinder without entering
this pipe or vessel, and from either end of this pipe or vessel at pleasure.
And I use this my method in the following manner :-First, I allow the
steam to enter the cylinder and press down the piston with condensation under
it in the common way; then, shutting the valve next the boiler, and also that
on the condenser below the piston, I open the valve on the enlarged pipe or
vessel, and allow the steam in the cylinder to unite with what remains in the
enlarged pipe or vessel from the former. stroke; when I shut the valve on top
and open that at its bottom, and allow the steam to pass under the piston, whilst
that steam which remains above it is permitted to pass off to the condenser
when the piston is thrown up in power, and the valve at the bottom of the
enlarged pipe or vessel is shut, which finishes this operation, during which I
should remark, the valve next the top of the cylinder is always kept open; but
when a greater power is required in the ascending stroke after the steam in
the cylinder has united with that contained in the enlarged pipe or vessel, the
valve next the cylinder is shut, and the communication between the boiler and
this enlarged pipe or vessel opened; and I admit the steam thus increased in
power under the piston (shutting it off from the boiler) to act as before men-
tioned; or I vary this method, and instead of communicating with the steam
pipe I have a small pipe, from near the bottom of the boiler, led through some
proper part of the fireplace, separate flue, or otherwise, and terminating by a
descent into the enlarged pipe or vessel aforesaid (which should also have a
descent into the cylinder), and having a valve at the opening next the boiler,
and another at a proper distance towards the aforesaid vessel, with a safety
valve on the part between them. Now I open the valve next the boiler, and
allow a portion of water to pass into this pipe, when I close it again, and when
the steam has passed from the cylinder into the enlarged pipe or vessel afore-
said, and is shut off, I open the vessel next to it on the small pipe, and admit

page_text: this strongly heated water into the enlarged pipe or vessel, and at the same
time I admit this invigorated steam into the cylinder under the piston, as
before described, and in this as in the first method the valve next the top of
the cylinder is kept open or omitted; thus working the engine with a double
stroke either with single steam only or with some addition to it. In some cases
where the stroke of the engine begins in greater power than it terminates;
which may be done by shutting off the steam at half the stroke or otherwise;
I apply some of the following machines; and where it is the alternate stroke
I want to regulate, I connect Fig. 1 with the main beam by the rod A, which is
attached to the pulley wheel B (which has flanches) by chains encircling.it in
opposite directions, and fixed to it; B turns on the axletree C, which has a
double crank D, and on each side of B there is a rochet wheel E and F fixed
on the same axletree, each rochet having two teeth, the teeth of E being in
the opposite direction to those of F; and on opposite sides of the rochet, but
parallel to those of F, B, is connected with E by a spring catch, and with F
by a movement catch, which is to be acted on by the inclined plane G, or any
appropriate stop, and so balanced as the position of the wheel requires. G is regu-
lated by the screw H. A loaded lever I is attached to each limb of the crank D
by a separate chain, the slack of wbich is taken up by balanced weights K, K.;
or the lever, according to circumstances, may be used below; the stroke may be
regulated either in the ascent or descent of A, and one half the revolution of B
constitutes the working stroke. Thus, the crank D being horizontal when the
stroke begins, A ascending turns B through a quarter of a circle, which raises
the lever I through half the stroke; A still rising, the lever sinks and assists A
through the remainder, when the inclined plane G, or other appropriate stop,
forces up the catch of F, and A descending carries back B to begin the next
stroke. The pulley wheel B may be sometimes varied from a circular form.
When I wish to regulate each stroke I apply different machines, according to
circumstances. I use a lever with a single crank with a pulley wheel fixed
to the axletree, attached by chains to the rod, as in Fig. 1, which only goes
through half a revolution and back again; or I apply Fig. 2, which is another
machine, to regulate the stroke by a loaded lever A acting on a fusee C, or
otherwise. It has two pulley wheels turning on the axletree in opposite
directions D and E, attached by chains in Fig. 1 to a perpendicular rod or
rods G. The two rochet wheels H and I are fixed to the axletrec, each
contains but one tooth; the teeth are parallel; each is connected with the
flanch of its pulley wheel by a moveable spring catch standing in the same
direction, which is struck up alternately at half the stroke by the moveable
stop K or L, which allows the catch to pass in one direction, but, resisting,

page_text: removes it in the other.
As the rod descends, raising the lever, the catch of
D holds in its rochet, whilst that of E slides back at half the stroke. The
catch of E first takes in its rochet, and the catch of D is struck up, when the
lever sinks, assisting the descent of the rod. In the reverse stroke the lever is
lifted, the action of the catches is reversed, and at half the stroke the lever
sinks, assisting the ascent of the rod; the catches should be so managed
that the one should be brought to hold on its rochet before the other is
struck up, either by placing them in precise situations or by changing their
situations by movements common to engines, as most convenient. If I wish
to expend the extra power of the beginning of the stroke on the air pump, I
work the lever A, Fig. 3, whose opposite limb exceeds the length of the stroke
of the engine, passing between two rollers fixed on a perpendicular rod
appended froin the mean beam. The limb of this lever should be made of
such a proper figure as to accommodate itself to the resistence.
And whereas horse whims have been constructed without a span beam, by
propping the cage, but which have not been found sufficiently strong and
secure, now at some distance beyond the whim, but if in a line with that and
the shaft the better, I erect a post, supported on the top by props or otherwise,
to which I affix a large block or pulley, and when the rope has been passed
round the cage I reeve it through this block or pulley and return it to the
pulley over the shaft. By this method the whim is placed nearer in equili-
brium than that of the old.
My next method is a metallic spring ring piston. A, Fig. 4, is a flat plate
with or without a valve, as near the size as may be of the cylinder or working
piece in which it is to act, so as to rise and fall with ease, through which are a
number of oblong holes, the number more or less proportional to its diameter,
and correspondent to the round holes in B, which is an elastic metallic ring, to
which ring when it is screwed it may slide freely through the range of the
oblong holes; B should be accurately turned and ground to suit the plate A,
and that having a saw cut through it as at C, it may spring to a circumference
somewhat larger than the working piece; the bottom A at C should be
brought out to the very extremity of B, guided by the screw on each side. D
is a vertical spring pressed to the side of the cylinder, or to a notch in each
end of the ring at E, E, by the screw F, on which is laid a plate entirely to
cover it, and screwed through the oblong holes in B into the bottom, to keep
the points of the spring D more absolute in the notches, or otherwise; there
may be also within it a spring G, taking into notches on the points of the
spring D.
Another method is shewn on H. Each side the saw cutt are two perfora

page_text: tions having solid segments inlaid in them; one end of each is fixed, the other
slides. A plate covers these as it doth the spring at B; sometimes a plate may
be laid or inlaid under as well as over. In all these cases great accuracy must
be observed to have all crevices well secured; there may be a packing applied
within the springs of B and segments of H, but cautiously; and between
A and B or A and H may be placed a layer of oily cloth, or any other fit
substance. Aud in cases where it may be proper, I apply the inner or concave
edge, the ring being first made to spring inward, and properly ground to suit
the part of the cylinder where it is to act, enclosing a rod or hollow or solid
plunger with or without valves. It may be necessary to observe that in the
forementioned machines where there are used a pulley wheel and chain, the
same kind of motion may be produced by a rack and wheel, or by a rack
wheel and pinion.
balls; D is an
At F a screw
G, G, G, is a
My method to prevent the mercury being affected by the leather bag in the
portable or marine barometer is by pressing the leather on the top of the
mercury instead of lifting it at the bottom, is shewn by Figure 5. a, a, a, is a
cylinder with its top and bottom made of ivory, wood, or any. proper substance,
but so that it should separate in three parts as at B, B, c, C, C. C, C, is a trough
into which the upper part is placed; D and E are two brass
ornament to correspond with E, which has a square hole in it.
is placed to prevent E from rising, though it admits its turning;
hollow space, and F, F, is a plate screwed against the wood at H, H; the bar
I, the upper part of which is square, its under part screwing through F, F, is
let through the plate K, and has a shoulder on each side of it, and is admitted
to turn round. The plate K is screwed to the plunger L, so that as E is
turned, L may rise or fall; M is a round hollow piece of wood with a groove
round its outside; N is a piece of leather, the middle part of which is cut out
so that it is nearly the size of the grove at the bottom of L; O is the tube
which, being nearly inlaid in the frame, and cemented or glued as far up as P,
and the wood or ivory a, a, a, being in its three parts, the outer edge of the
leather N is gathered, glued, and bound into the groove of M (the piston
being out), and then likewise glued into the space of the upper G, G; the
piston being now screwed up through F, the inner edge of the leather N is
likewise glued and bound into the groove at the bottom of the piston, and the
wood or ivory between C & B, is glued over it; and all that part glued to the
frame in its proper place, being very careful to leave no crevice or opening.
The frame being inverted, the inner part of the tube should now be cleaned
and filled with mercury, as should also be a considerable space of the bottom
G. The trough should now be glued carefully on, so that no mercury can

page_text: possibly escape. When the glue is perfectly hard the instrument should be
brought perpendicular, taking the direction of keeping its face upwards; the
screw hole at Q (which has a large turned milled head and wide hollow
shoulder, to cover a small incision at R, through which the air passes when
the instrument is in working), is now opened, and the surplus mercury taken
out; N, L, M, represent the hollow wood piston and leather brought near its
proper form; R, R, are two pieces of polished metal brought over the cylinder
to secure it to the frame through the screw holes; S, T, is an additional piece
to unite them when on. The screw Q should be made of wood, ivory, iron, or
steel, as the other metals would amalgamate with the mercury. When this
instrument is wanted to be removed, first fix the screw Q very tight, then turn
the ball E till the mercury rises to the top of the tube; when it is again put in
its place, first let the mercury down by unscrewing E, then unscrew
one or two turns.
about
My method of uniting the compass and vertical are in one box, so as to
render them exceedingly portable, is by placing the vertical are under the
cover, and is represented by Figure 6. At A, A, are two pieces of metal
or other proper substance inlaid in the cover, and screw holes and cut
through them, into which the screws B, B, after having gone through a plate
C, C, enter. C, C, is the back or frame to which the vertical arc is screwed,
and it traverses under the spring D, which is kept close by the screw on D.
The vertical arc is graduated in the usual way, and may be transferred from
the inside to the outside of the cover, by unscrewing B, B, on the inside, and
placing them outside; opposite the sights, &c. are places cut in the box to
receive them when closed; E is a perforated plate screwed to the box, in
which the slide F moves, carrying with it G, the other end of which is screwed
to the cover; it should be so made that when raised, the cover should produce
a right angle with the box. There are two milled edge screws in G to fasten
it; other sights may be applied to the opposite side of the cover, and the per-
forated brass E graduated so that G may be its index to ascertain the altitudes.
This may also be effected by inlaying a semicircle of brass in the cover; or
the whole cover made of brass, and a semicircle formed either inside or outside,
and a right-angled piece of metal baving sights on it made to traverse as its
index. A plumb line or spirit level as at H, and another in the direction of
I, K, may be properly applied to it. And whereas particles of an irony nature
have affected the traverse of the needle in horizontal circles, I prefer a needle
a quarter of an inch (more or less) shorter than they are usually made, and
that deficiency made up of gold, silver, or any proper substance not subject to
magnetic attraction.
"

page_text: My method of taking angles either with or without a needle is shewn by
Figure 7. A is a raised brass graduated rim, supported on a ball and socket
hinge in the usual way; the cylinder B is let down into it, and traverses freely,
but is prevented from rising by points of screws entering through A into a groove
in it; on the top of B is another graduated rim similar to that on A, and as the
arrow on B is the index of the graduated scale on A, so as the arrow on the
sights on C, the index to the graduated scale on B. On the top of C is a
compass, to which are affixed the sights D and E in the usual way. The
perpendicular perforation F, and another which is opposite to it, are used as
sights likewise, so that when one object is taken through the sights on B,
another object may be also taken through the sights on C, and then both be
examined without the instrument being moved,
My method of ascertaining distances and bearings on a sphere or globe is as
follows: A, Figure 8, is a globe; B is a brass meridian, which may be
perforated nearly from one end to the other, and that traverses round the
globe attached at each end to a centre, one of which represents the north, the
other the south pole; on this meridian is a sliding compass C, having on it
the degrees and points; the compass does not turn on its own centre on the
meridian B, but is carried with it round the sphere, consequently the different
points always keep their respective directions; on the compass C is a graduated
measurer D, and both attached to the meridian B by a mill-headed screw.
may be used thus, the distance and bearing of two places on the globe
required to be known, bring the meridian B to any convenient place com-
manding them, and turn the measurer, which is also a segment of a globe, to
touch the said places. Their distance is then shewn on the measurer, and
their bearings on the compass of this globe gonometer.
It
My next impreved instrument, which I call the gonometer or anglometer,
nearly resembles the common sector, having two limbs A and B, the inner
edges of which are graduated into a scale of equal parts; on its centre is a
traversing wheel, the circumference of which is divided into three hundred and
sixty degrees, and includes the points of the compass. It has in general one
slide D, precisely parallel with its inner edge, on which is a wheel similar to the
preceding one, having on it a moveable brass limb c, with a scale corre-
sponding with the graduated edges. It has also on its reverse side a scale for
dividing circles (somewhat in the same manner as the line of lines on the
sector) by taking the radius in the compass and applying each foot thereof to
its correspondent point on each limb of the instrument, and with that opening
take the division required. The quantity of an angle ascertained by the anglo-
meter is as follows:-A hill being elevated thirty degrees, and measuring two

page_text: hundred and twenty fathoms on its ascent, its height is required. Set A at
thirty degrees with B (the limb C being set at a right angle with A, which is
done by bringing 0° in the sliding compass against the arrow on the slide, and
C to ninety degrees on its compass), then bring the limb C to two hundred and
twenty on B, and its height will be denoted on C.
When I mentioned that I worked the lever Figure 3 to expend the extra
power of the stroke of the engine in aid of the air pump, I should have
observed that I likewise use the extra water from the condenser, after having
reserved sufficient for the boiler, for the same purpose in plates congenial to
it, by conducting it by a pipe, launder, or otherwise, through, on, or upon some
machine applicable for that purpose. The metallic piston in both cases. may
have a plate similar to A, Fig. 4, on its opposite side, inclosing it between
them; they may also include a packing properly adapted for their purpose.
In witness whereof, I, the said Robert Dunkin, have hereunto set my
hand and seal, this Twenty-ninth day of July, in the year of our Lord
One thousand eight hundred and thirteen.