CERTAIN IMPROVE- ·MENTS IN THE CONSTRUCTION AND MANUFACTURE OF SPRING JACKS, AND THEIR CONNECTION WITH ROASTING APPARATUS
Year: 1822

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
PEARSE, of Tavistock, in the County of Devon, Ironmonger and Clock and
Watch Maker, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth did, by
His Letters Patent under the Great Seal of that part of the United Kingdom
of Great Britain and Ireland, called England, bearing date at Westminster,
the Twenty-ninth day of July, in the third-year of His reign, give and grant
unto me, the said John Pearse, my exors, adññors, and assigns, His especial
licence, full power, sole privilege and authority, that I, the said John
Pearse, my exors, adñiors, and assigns, during the term of years therein
mentioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, and also in all His
Majesty's Colonies and Plantations abroad my Invention of "CERTAIN IMPROVE-
·MENTS IN THE CONSTRUCTION AND MANUFACTURE OF SPRING JACKS, AND THEIR
CONNECTION WITH ROASTING APPARATUS;" in which said Letters Patent there is
contained a proviso, that if I, the said John Pearse, 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 Majesty's High Court of
Chancery, within six 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, shall utterly cease, determine, and
become void, as in and by the same, relation being thereunto had, will more
fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
John Pearse, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are particularly described
and ascertained in and by the Drawings hereunto annexed and the following
description thereof (that is to say) :-
My improvements in the construction and manufacture of spring jacks and
their connection with roasting apparatus consist, first, in a mode of combining
a train of tooth'd wheels with a spring barrel, so as to produce a regular and
continued rotatory motion without the employment of a fuzee or chain,
and, secondly, in a mode of connecting this mecanism to a roasting spit and
thereby causing it to revolve, which will be understood by a reference to the
Drawings hereto attached, and the following description.
Figure 1 represents a roasting screen with the spring jack attached thereto
by means of thumbs screws or any other convenient mode. Figure 2 shows
the internal construction of the jack, the front plate being removed for the
purpose of exposing the wheels. Figure 3 is a side view or profile of the jack
by which the thickness of the respective wheels and of the whole apperatus
will be clearly seen; and Figure 4 is the external appearance of the jack,
the plate covering the parts shewn at Figure 2, the Drawing of these three
Figures being made to half the size of jack itself; a is a box with a broad
convolate spring of plate steel coiled within it, commonly called a spring
barrel, one end of which spring is secured to the interior of the box or barrel
and the other end to the axle b, b; at the end of this axle a ratchett wheel c is
affixed which is preventing from reterograding by the fall d, held in the
rotchett by its spring e (when the spring is wound up, which may be done by
a winch applied to the axle, the barrell a revolves in the direction of the
arrow); a toothed wheel forming part of this barrel takes into a pinion f, upon
the axle of which the tooth'd wheel g is affix'd; g takes into pinion h, upon
the axle of the tooth'd wheel i, and i having oblique teeth takes into the
endless screw k. Hence the power of the spring barrel a exerting itself upon
this train causes them to turn with different velocities according to the number
of their teeth respectively.; at the top of the endless screw shaft the fly wheel
7 is attached which regulates the motion of the train.
The mode by which this rotative power is communicated to the spit will be
seen as follows:-The teeth of the barrel wheel a take into a pinion m, to the
axle of which the tooth n is affix'd, and when the spit is suspended in the
screen, as shewn at Figure 1, the tooth'd wheel o attach'd to its end is acted
upon by the teeth of n, and by that means made to revolve with a uniform
motion suited to the purpose of roasting.

page_text: This improved spring jack is very small compared to its power, is simple in
its construction and is perfectly capable when wound up of turning a joint of
meat weighing 25lb. and of continuing to go from 30 to 40 minutes without
requiring to be attended to.
Having described the various parts, wheels, pinions, &c. of the mecanism,
I wish it to be understood, that I do not claim them indivudially as my
Invention, but merely their combination to the purposes of a spring roasting
jack, the particular features of my Invention being the combination and
opperation of the train without a fuzee, and the connection of the spit to this
train by means of a tooth'd wheel; which particular, being to the best of my
belief new or never before employ'd in connection with a spring roasting jack,
I claim as my Invention.
In witness whereof, I have hereunto set my hand and seal, this Twenty-
seventh day of January, One thousand eight hundred and twenty-