IMPROVEMENTS IN STEAM ENGINES
Year: 1858

page_text: LETTERS PATENT to Joseph Bunnett and Joseph George Bunnett, of
Deptford, in the County of Kent, Engineers, for the Invention of
"IMPROVEMENTS IN STEAM ENGINES."
Sealed the 1st November 1858, and dated the 7th May 1858.
PROVISIONAL SPECIFICATION left by the said Joseph Bunnett and
Joseph George Bunnett at the Office of the Commissioners of Patents,
with their Petition, on the 7th May 1858.
We, JOSEPH BUNNETT, and JOSEPH GEORGE BUNNETT, of Deptford, in the
County of Kent, Engineers, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN STEAM ENGINES," to consist in certain improvements
in a peculiar form of steam engine, for which Mr. Joseph Bunnett obtained
Her Majesty's Royal Letters Patent, bearing date the 14th day of June 1838,
and to which he gave the name of a concentric steam engine.
The present improvements consist in the employment of a solid annular
piston rod working round a circular guide instead of on a central axis as
heretofore, also in placing the steam-ways- in the central part of the engine,
and working the same by a single slide, which renders the two slide valves

page_text: with their connecting gear formerly employed unnecessary, and also enables
the whole of the internal working parts to be got at by taking off one side
covering plate without disturbing any other part of the engine.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Bunnett and Joseph George Bunnett in the Great
Seal Patent Office on the 6th November 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOSEPH
BUNNETT and JOSEPH GEORGE BUNNETT, of Deptford, in the County of Kent,
Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of May, in the year of our Lord One
thousand eight hundred and fifty-eight, in the twenty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto us, the said
Joseph Bunnett and Joseph George Bunnett, Her special licence that we, the
said Joseph Bunnett and Joseph George Bunnett, our executors, admini-
strators, and assigns, or such others as we, the said Joseph Bunnett and
Joseph George Bunnett, our executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands and Isle of Man, an Invention for "IMPROVEMENTS IN
STEAM ENGINES," upon the condition (amongst others) that we, the said Joseph
Bunnett and Joseph George Bunnett, our executors or administrators, by an
instrument in writing under our or their hands and seals, or under the hand
and seal of one of us or them, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that we, the said Joseph Bunnett and Joseph George
Bunnett, do hereby declare the nature of the said Invention, and in what
manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof, that is to say :-
These improvements have reference to a peculiar form of steam engine, for
which Mr. Joseph Bunnett (one of the present patentees) obtained Her Majesty's

page_text: Royal Letters Patent, bearing date the 14th day of June 1838, and to which
he gave the name of a concentric steam engine. The present improvements
consist in the employment of a solid annular piston rod working round a
circular guide instead of on a central axis as heretofore; also in placing the
steam-ways in the central part of the engine, and working the same by a
single slide, which renders the two slide valves with their connecting gear
formerly employed unnecessary, and also enables the whole of the internal
working parts to be got at by taking off one side covering plate without
disturbing any other parts of the engine.
And in order that the same may be more fully understood, reference is had
to the Drawings hereunto annexed, and to the letters and figures marked
thereon, that is to say:-
Figure 1 is a front elevation, Figure 2 a sectional plan view, and Figure 3
a vertical section of a double steam engine constructed agreeably to our said
improvements, composed of two separate engines united, and capable of being
worked together, or either of the engines may be worked separately and
independently of the other. The same letters refer to similar parts in each
of these Figures. A is the frame or standard on which the engine is mounted;
B, the cylinder or steam chamber in which the piston works; C, the piston,
forged solid with the guide ring or annular piston rod d, d, and packed in the
usual manner; E, E, are the steam-ways; and f, the exhaust passage, formed
in a solid central blocking or guide e, e, upon which the annular piston rod
d, d, works. The exhaust passage f passes through the central blocking or
guide e, e, and in a single engine may be led off from the back of the engine
in any convenient direction, but when two engines are combined, as here
shewn, the exhaust passages are, by preference, led into a breeching g, which
terminates in an outlet h.
G is the connecting rod from the piston rod d to
the crank shaft H, upon which a fly wheel is placed, if desired; I is an
eccentric for working the slide valve K; L is the steam pipe; m, m, are
covering plates at the sides, the removal of which gives access to the internal
working parts of the engine; n, n, are stuffing boxes through which the
annular piston rod d, d, works. This engine may be worked either as a high-
pressure or as a condensing engine, and may be fitted with the ordinary starting,
reversing, and expansion gear, if required, as is well understood by engineers.
But these, as well as many other details of construction and arrangement,
may be varied according to circumstances without prejudice to the character
of our Invention.
And we desire it to be understood that what we claim as constituting our

page_text: improvements is the construction of concentric steam engines substantially as.
berein-before described, and shewn in the accompanying Drawings.
In witness whereof, we, the said Joseph Bunnett and Joseph George
Bunnett, have hereunto set our hands and seals, this Sixth day of
November, in the year of our Lord One thousand eight hundred and 5
fifty-eight
JOSEPH BUNNETT.
(L.S.)
Witness,
JOSEPH GEORGE BUNNETT. (L.S.)
W. BADDELEY, Patent Agent,
Islington.