NEW METHOD OF CONSTRUCTING A ROASTING JACK
Year: 1825

page_text: THIN'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
THIN, of the City of Edinburgh, Architect, send greeting.
WHEREAS His present most Excellent Majesty King George the Fourth
dil, by His Royal Letters Patent under the Great Seal of the United Kingdom
of Great Britain and Ireland, bearing date at Westminster, the First day of
February, in the sixth year of His reign, give and grant unto me, the said
John Thin, my executors, administrators, and assigns, His especial licence, full
power, sole privilege and authority, that I, the said John Thin, my executors,
administrators, and assigns, during the term of years therein expressed, should
and lawfully might make, use, exercise, and vend, my "NEW METHOD OF
CONSTRUCTING A ROASTING JACK," within England, Wales, and the Town of
Berwick-upon-Tweed, in such manner as to me, the said John Thin, my
executors, administrators, and assigns, should in our discretion seem meet; in
which said Letters Patent is contained a proviso that if I, the said John Thin,
should 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 Majesty's
High Court of Chancery within two calendar months next and immediately
after the date of the said Letters Patent, that then the said Letters Patent,
and all liberties and advantages whatsoever thereby granted, should utterly
cease, determine, and become void, as in and by the said recited Letters
Patent, 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 Thin, do hereby declare that the nature of my said Invention, and in
what manner the same is to be performed, are particularly described and
ascertained in the Drawing hereunto anuexed, and the following description
thereof and references thereto (that is to say) :-

page_text: The principle of the said Invention consists in the application of the vaned
wheel of the smoke jack to the current of heated air and smoke in a vent or
chimney in such manner that the wheel shall revolve in a vertical instead of a
horizontal direction. This movement, while it is equally powerful with the
horizontal, requires less machinery and fitting, and in respect that all the
friction is out of the reach of the heat and soot, much less cleaning and much
less oil. The machine is, moreover, capable of being fitted into any common
sized vent or chimney even already constructed with very little trouble. To
realize the said principle into a construction or machine,-the construction of
which as realizing the principle I alone claim as Invention, and none of the
parts to be enumerated which are quite common,-I take an axle or spindle of
cylindrical form, which is the best of iron, or any other suitable metal, about
half or three quarters of an inch in diameter, and from fifteen to twenty inches,
or more or less in length, as may suit the box or case, to be described in the
sequel, into which it is to be placed. Round the circumference of the middle
point of this axle, and at right angles to the axle's length, on points of the
circumference at equal distances from each other, and radiating from the axlo
like the arms and paddles of the wheel of a water mill or steam boat, I fix
about eight or ten slender arms, of iron or other suitable metal, in weight as
nearly equal to each other as possible, and several inches in length, as required;
to the outer extremity of each arm or spoke, and in the plane of the length of
the axle, I attach a vane of rolled iron or other suitable metal, the thinner
and lighter, if sufficiently strong, the better, about twelve inches in breadth,
across the spoke or arm, and ten in depth, or more or less, according to the
size of the box or case above alluded to (see Figure 1). These vanes to be
equal in weight, or as nearly so as possible, to each other, so that none may
preponderate. I make a case or box of rolled iron, or other suitable metal or
material, with three close sides, one of them curved, between two that are flat,
the curved side being a segment of two thirds of a circle, or nearly so. The
fourth side I leave open with a flange round it, and it presents an oblong
rectangular opening or parallelogram, the long sides of which as streight lines
subtend the arch or segment of the two thirds of the circle already described.
The diameter of the said circle (if completed) would be about two feet and a
half, or less or more, according to the size of the vent which will regulate the
diameter of the segment, while the breadth of the curved side or rim may be
from twelve to fifteen inches, or more or less, so that it shall be a little less
than the width of the vent or chimney. The box resembles externally a mill
stone or common flat cheese, with one third taken off by a cut streight across,
but is quite hollow and free within. In each of the flat sides, in the centre of the

page_text: circle of which the curved side of the case or box forms two thirds, a perforation
is made, through which the axle already specified passes from one flat side to
another, and out beyond the sides a few inches less or more at pleasure. The
extremities of the axle are carried into bushes of brass, or other suitable
metal, in which they revolve; thes bushes are firmly fixed to the flat sides of
the case, or box, or flange. The revolution of the axle will of course carry
the vanes successively round in a complete circle two thirds within and one
third without the case or box, and care must be taken to regulate to each
other the size of the box and of the vanes in such a manner as that the vanes
may revolve freely, but as near the sides, both curved and flat, of the box as
possible (see Figure 2). Upon one or upon each end of the axle, according as
fewer or more spits are required to be turned at the same time, and either
between the box and the bush or beyond the bush, but rather the first, I fix
a small pinion of cast iron, brass, or other suitable metal, about an inch and a
half diameter, and about half an inch across the rim. A toothed wheel of the
same metal, with the pinion, or other suitable, about from eight to twelve inches
in diameter, and about half an inch across the rim, is fitted to and turned by
the same pinion, lies parallel to the flat side of the case or box, and revolves
in the contrary direction with the vanes within the box (see Figure 3). The
pinion may be fitted to turn a wheel in the direction at right angles to that
direction, the spits moved by which will in consequence have a position at
right angles to those turned by the wheel in the first position above specified.
From the centre of this wheel, and fixed into it, projects outwards only, another
axle, which goes round with the wheel, and turns at its other extremity in a
perforation or bush in a bridle or cross bar attached to the flat sides of the
box by two bars, one on each side, of about the same length with and parallel
to the said outer axle. The said outer axle and bridle are made of iron or
other suitable metal, from half an inch to an inch in thickness, or more or less,
as wanted for strength. On this axle one or more common jack pullies are
fixed, cach of which, by means of the common endless chain, turns a spit in
the ordinary way, the spit lying horizontally and with the substance roasting on
it revolving vertically. When the wheel turned by the pinion revolves in a
plane at right angles to that now described it will turn a vertical spit or sus-
pending line, and the substance roasting on it horizontally. (See in higure 4 a
view of the box as open to the vent, with the axle, vanes, pinion, wheel, outer
axle, bridle, and pullies; also in Figure 5 a view of the box as seen from the
kitchen.)
To fit the construction or machine just described more conveniently to its place
mom side of the race or how he two or more

page_text: strong hinges fixed in the flange at one extremity of its curve, and by a chain
and pulley at the other to a frame of cast iron or other suitable metal, of
aperture just sufficient to be filled up by the box when the edges of its open
side are brought close to it, and of depth a few inches, to be built firm into an
opening made or left in the front wall two or three feet over the fireplace, the
said pulley being the uppermost and the hinges the lowest point, so that the
curved side will present itself vertical in front and the flat sides also vertical
on the right and left. The size of the apparatus having been regulated
accordingly, the exposed vanes, when placed in the vent, will be in the middle
of the stream or current of the heated air and smoke, and being propelled
upwards in succession will revolve vertically, while the whole external surface
of the case or box, with all the apparatus attached externally to it, as abovo
specified, will be in view on the outside of the wall of the vent. In order to
afford the means of contracting or enlarging at pleasure the channel of the
vent for the heated air and smoke, the said frame is gradually enlarged on both
sides from a point up the sides about a foot from the lower extremity till it
extends backwards into about the middle of the vent, its head being shaped to
fit a double curved flap of suitable metal, and of the breadth of the frame,
which, by means of a sliding bar on cach side, can be drawn close to the
frame or pushed to the back of the vent (see Figures 6 and 7). To allow the
vent to be swept, the box, with all attached to it, both inside and out, folds
down by the hinges already described, and is supported at the other end by the
chain or cord from the pulley at the top, which draws out to the necessary
length, and the built-in frame being then left open, is filled up by a sheet-iron
or wooden or other door. The vent being then free, a slip or sliding door is
fitted into the front of the curved side of the case or box, which may be pushed
aside and an opening uncovered, through which the vanes can be successively
swept on both surfaces without lowering down the box on its hinges.
In witness whereof, I, the said John Thin, have hereunto set my
hand and seal, this Twenty-third day of March, in the year of our
Lord One thousand eight hundred and twenty-five.

page_text: Thomas Megget, of Edinburgh, W.S., maketh oath and saith, that he was
present and did see John Thin, of the City of Edinburgh, Architect, sigu.
seal, and as his act and deed acknowledge and deliver, a certain Deed Poll u
Instrument in Writing hereunto annexed, bearing date the Twenty-third day of
March instant, purporting to be a Specification describing and ascertaining the
nature of the said John Thin's Invention of a New Method of Constructing
a Roasting Jack; and this Deponent further maketh oath and saith, that the
name "John Thin," set at the foot of the said Deed Poll as the party
executing the same, is of the proper handwriting of the said John Thin, and
that the names or characters "Tho. Megget" and "Tho Corbet," indorsed
on the said Decd Poll as Witnesses to the signing, sealing, and delivery thereof,
are of the respective handswriting of the said Tho. Meggett and Tho' Corbet.
TRO MROORT