IMPROVEMENTS IN STEAM ENGINES
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
CURZON, of the Borough of Kidderminster, in the County of Worcester,
Machinist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-eighth day of January, in the third year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said
Henry Curzon, Her especial licence, full power, sole privilege and authority,
that I, the said Henry Curzon, my exors, admors, and assigns, or such
others as I, the said Henry Curzon, my exors, admors, or assigns, should
at any time agree with, and no others, from time to time and at all times
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, and also in all Her said Majesty's Colonies and
Plantations abroad, my Invention of "IMPROVEMENTS IN STEAM ENGINES;"
in which said Letters Patent is contained a proviso that I, the said
Henry Curzon, shall 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
Her said Majesty's High Court of Chancery within six calendar months next
and afnediately after the date of the said in part recited Letters Patent, as in
and by the same, reference being thereunto had, will more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Henry Curzon, do hereby declare 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 following statement thereof (that is to say) :-
My Invention relates to a mode of working steam expansively by combining

page_text: three or more cylinders, the pistons of which succeed each other at equal
distances, to work one shaft or axis, whereby greater uniformity of power will
be exerted throughout the revolution of such shaft or axis than can be obtained
by the modes now resorted to for constructing steam engines to work with
steam expansively; and in order to give the best information in my power, I
will proceed to explain more particularly the nature of my Invention in
working steam expansively, as at present practised. It is for the most part
employed in a single cylinder wherein the steam is only permitted to flow for a a
very short portion of the length of stroke of the engine, and by such means the
steam is allowed to expand to the most advantageous extent, and by which
very beneficial results have been obtained, particularly in Cornwall; but in such
cases uniformity of power during the revolution of a shaft or axis is not
obtained or required; but such constructions of steam engines are not appli-
cable to manufacturing purposes, nor for the propelling of vessels where much
greater uniformity of power is required to be communicated to a shaft or axis
during its complete revolution, and it has long been considered desirable to
construct steam engines for manufacturing purposes, and for propelling vessels,
which should obtain the advantages of working steam expansively, and not
materially prejudice the equality of power during the revolution of a shaft or
axis when actuated by the working of two steam cylinders; but all attempts to
use steam expansively to any considerable extent has failed, when using only
two steam cylinders to drive a common shaft or axis, owing to want of unifor-
mity of power to the axis in its whole revolution; hence, in using steam.
expansively for manufacturing purposes, as at present practised, only a very
limited benefit can be obtained when so working steam expansively, owing to
the comparatively small space which the steam has to expand into. Now,
the object of my Invention is to combine three or more steam cylinders to the
working of a common axis or shaft, that in each cylinder the steam may be
used expansively through the most considerable part of the length of stroke,
and the steam being permitted to flow into each cylinder for comparatively a
very short part of the length of stroke. The constructing of steam cylinders,
with their pistons and piston rods, their slides or valves, with the requisite
means for cutting off the steam at any point of the stroke, being well under-
stood, it will not be necessary to enter into any description thereof, more
particularly as my Invention does not relate to any peculiarity of construction
of a steam cylinder or parts worked thereby, and the same may be said with
respect to condensers and air pumps and other parts suitable for steam engines,
my Invention simply consisting of combining three or more steam.cylinders to
work a single or common axis or shaft, in such manner that each piston shall

page_text: start from the end of its cylinder so as to work at all times at equal distances
apart, succeeding each other, and as nearly as possible, according to the fol-
lowing rule-If the steam engine is to consist of three steam cylinders, then,
they being each connected by the ordinary well-known means to the shaft or
axis to which they are jointly to communicate motion, and in such manner that
one piston precedes the next by a distance equal to one third of the length of the
stroke, the cylinders being all of the same diameter and length of stroke, and
the sides or valves of each cylinder are to be so arranged as to cut off the
steam at one third of the stroke, as is well understood; hence, by this arrange-
ment the steam in each cylinder will be worked expansively two thirds of the
stroke, and, owing to the mode of combining the three cylinders, there will at all
times be one or other of the pistons working by the pressure of steam
through the first third of the length of the cylinder, another cylinder will be
working with the steam expanding through the second third of the length of
stroke, and another cylinder will be working with the steam expanding
through the third third of the length of stroke; and it will readily be seen
that, supposing the pressure on the whole area of the three pistons to be taken
at different points of the rotation of the shaft or axis to which the three steam
cylinders are communicating motion, much greater uniformity of power will be
found to prevail at all points of motion than could heretofore be obtained when
working steam expansively. I would remark, that I prefer that the steam
should be worked at about forty-five pounds on the square inch, as I believe
that pressure, under all circumstances, has been found the most advantageous
when working steam expansively in Cornwall, where the greatest benefits have
been derived by thus working steam; but I do not confine myself thereto, as
higher or lower steam may be employed. In working steam expansively, when
the greatest advantages have been obtained, the steam has been cut off very
early in the stroke, even from one eighth to one sixth, and thus allowing the
steam to expand seven eighths to five sixths; and I am aware, that to carry.
out my Invention to the full extent would involve the using of as many steam
cylinders as the number of times the original quantity of steam is allowed to
expand into, but such a combination would involve the occupying of more
space and the using of more parts than would in most cases be compensated for
by the savings consequent on the small additional expansion thereby obtained,
and so far as I have been enabled to ascertain the fact, it is better to cause the
steam to be cut off earlier in a less number of cylinders than to have as many
cylinders as the number of times the bulk of steam which is allowed to flow
into a cylinder is allowed to expand itself into. Thus, in combining four steam
cylinders to work a single axis or shaft, the cutting off the steam at one fourth

page_text: of the stroke, and causing the pistons to precede each other at a distance equal
to one fourth of the length of stroke, great uniformity of power will be obtained
to the axis or shaft during the whole of its revolution; at the same time in
using four steam cylinders so combined, with reference to the axis or shaft as
above described, but having the slides or valves to cut off the steam at some-
thing less than a fourth and even down to a sixth, or less of the stroke, will not
very prejudicially alter the uniformity of the power through every point of the
revolution of the common axis or shaft, and consequently comparative
uniformity will be gained with the least number of cylinders, and very great bene-
fits obtained by using steam expansively. I would, however, remark, that, where
great nicety of equality of power is required to act in driving a common axis or
shaft, the number of cylinders should be equal to the number of times one
measure or quantity of steam is permitted to expand itself into.
Having thus described the nature of my Invention, I would remark, that
what I claim is, the mode herein described of working steam expansively in
steam engines, by combining three or more cylinders to work a common axis
or shaft in such manner that the pistons of the various cylinders precede each
other a distance equal to a third, a fourth, or other proportion of the stroke,
equal number of cylinders employed to drive such common axis or shaft, and
where the steam is cut off at or about a third, a fourth, or at other length of
the stroke, according to the number of cylinders combined, or at a length of
the stroke less than the number of cylinders used, as herein explained.
In witness whereof, I, the said Henry Curzon, have hereunto set my hand
and seal, this Twenty-second day of July. One thousand eight hundred
WEBERDERED,
I wenty-second day or July, in the
year of our Lord 1840, the aforesaid Henry Curzon came before our said
Lady the Queen in Her Chancery, and acknowledged the Specification afore-
said, and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Inrolled the Twenty-eighth day of July, in the year of our Lord One
thousand eight hundred and forty.