CERTAIN IMPROVEMENTS IN GENERATING STEAM
Year: 1825

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
M CURDY, of Cecil Strect, Stand, in the County of Middlesex, Esquire,
send greeting.
WHEREAS His present most Excellent Majesty King George the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-seventh day of December, in the sixth year of
His reign, did, for Himself, His heirs and successors, give and grant unto me,
the said John McCurdy, His especial licence that I, the said John M° Curdy,
my exors, aduiors, and assigns, or such others as I, the said John McCurdy,
my exors, adors, or assigns, should at any time agree with, and no others,
from time to time and at all times hercafter 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 His
said Majesty's Colonies and Plantations abroad, my Invention of "CERTAIN
IMPROVEMENTS IN GENERATING STEAM;" in which said Letters Patent is con-
tained a proviso obliging me, the said John M Curdy, by an instrument in
writing under my hand and seal, particularly to describe and ascertain the
nature of my said Invention, and in what manner the same is to be performed,
and to cause the same to be enrolled in His said Majesty's High Court of
Chancery within six calendar months next, and immediately after the date
of the said recited Letters Patent, as in and by the same, reference 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 McCurdy, 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 Drawing hereunto annexed, and the following
description thereof (that is to say) :—
My Invention of "Certain Improvements in Generating Steam" consist in
a new combination of materials, or the adaption and application of old and
well-known substances to produce or effect a particular purpose, which is both
novel and useful, and which from their form I denominate Franklin duplex
steam generators and steamometers; for this purpose I construct one or more
vessels or cylenders of any given number, length, or diameter (proportionate
to the size of the engine or quantity of steam wanted), made of wrought or cast
iron or other material of sufficient strength, inside of each of which vessels or
cylenders I insert or suspend in the centre another vessel or cylender of a
still smaller size, made of similar materials, leaving a small space on all sides
between the outer and inner vessels or cylenders, which I call the water line;
this space varies from half an inch to an inch and an half inch, which is thought
sufficient for generators of the largest size, but if necessary, may be still
further encreased. When the duplex generators are made of small size, the
inner vessel or cylender is rendered steam-tight by being closed at both ends;
but where the size of the generators are much enlarged, the space between the
outer and inner vessels or cylenders is closed at the ends only, and the centre
of tho inner vessel or cylinder may be used either as a fire-place or as a return
flue for the fire placed beneath them, for the purpose of placing the inner
vessels or cylenders conveniently winthin the outer oues; a head may be
attached to one or both ends of the vessels or cylenders that can be removed at
pleasure. The inner vessels or cylenders are kept in their places, or at certain
and proper distances from the outer ones, by means of bands or pins placed upon
them at intervals, of the same thickness as the space intended to be preserved
between them for the water line, but not so as to interrupt the passage either
of the steam or water. These double vessels or cylenders are connected by
pipes or tubes leading from the upper part or end of one generator to the
upper part or end of the next, in the whole set through which the steam and
water passes. I place these vessels or cylenders thus arranged, and which I
term duplex steam generators, in a common heated furnace, in the same
manner as gas retorts, or in the most advantageous mode for beating; I next
attach or connect to a set of the duplex generators, by means of a pipe or tube,
another vessel, which I term a steamometer, which vessel is intended to con-
tain steam only, and ought to contain at least ten times the solid contents of

page_text: the working cylender of the engine; the steamometer is connected to the
engine by the eduction tube for the passage of the steam, which eduction tube
is placed or inserted in the lower side or end of the steamometer. In the
Drawing A', A2, A3, A4, &c., represent eleven duplex generators, each twelve
feet long and twelve inches in diameter, set in a furnace; the upper vessel
No. 12, is the steamometer, and is intended to be of the same length, and
thirty inches or more in diameter; B, B, represent two interior vessels or
eylenders closed at both ends. The large vessel or steamometer No. 12, is
intended to contain the whole of the steam generated in all the generators for
the supply of the engine, or for other purposes. C represents the water pipe
leading to the pump or pumps; D is the pump; E the steam or eduction
pipe leading from the steamometer to the engine; M represents the safety
valve; N, N, represent an end view of two of the duplex generators, with the
flanges removed, the upper one with the inner vessel closed at both ends, the
lower open in the centre to allow the fire to return through it. The water is
introduced by a forcing pump into the generator A' by the pipe C, and is
forced and destributed around the space between A and B, which is represented
by a white line, and is termed the water line in all the generators untill it
reaches the heighth where the connecting pipe is inserted, out of which gene-
rator the water will flow or be forced into No. 2, and so on to No. 11. The
whole of the generators ought to be filled with water up to the heighth where
the connecting pipes are inserted, previously to kindling the fire, and whilst
the steam is generating, kept full up to that point. The water injected by the
pump at C, is thus spread in a thin sheet and exposed to a heated surface
equal to about 400 superficial feet (in this set of duplex generators) of the
outer vessels or cylinders, besides the surface of the inner ones, the steam is
consequently generated with astonishing and proportionate rapidity, and collects
in the steamometer, out of which it passes into the engine, or elsewhere,
through the eduction tube E, inserted in the lower part of the steamometer.
The Patentee claims as original in this combination, to produce the desired
effect, first, the construction of the duplex generators for the generation of steam
only in such a manner, by inserting one vessel or cylinder within the other) as
to expose a small quantity of water to a large heated surface by leaving a very
minute space or passage for water between the outer and inner vessels or
cylenders.
Secondly, he claims as original in this combination the steamometers or
separate vessels for containing the steam only, with the eduction pipe placed in
the lower part, to prevent the possibility of any accumulation of water.

page_text: Third, he claims as original in this combination the bands or pins on the
inner vessels or cylenders, filling the space at intervals between the outer and
inner vessels, to produce the water line, and to keep the inner vessels at proper
distances from the outer ones.
The advantages of this plan are, that the water being destributed in a thin
sheet over the whole surface between the outer and inner vessels or cylenders
up to the line of the connecting pipes, and exposed in every part to the imme-
diate action of the fire in tho duplex generators, the steam is generated with
amazing rapidity, the weight as well as the body of water in a boiler is avoided,
and consequently the danger from explosion; for no greater quantity of water
could be contained in a set of the duplex generators, however numerous or
large, than would fill the spaces between the outer and inner vessels up to the
line of the connecting pipes. The duplex generators occupy but little space,
and require but a small proportion of fuel compared with boilers to produce
the same power. The steam may be generated in a very short time after the
fire is made, may be encreased at pleasure to any requisite height or pressure,
and used without danger. The Patentee would remark that, if necessary,
separate pipes for the passage of steam may be attached to each or any number
of the generators to convey the steam to the steamometer, besides the general
tubes of communication from one to another; that a number of the duplex
generators may be attached to the ordinary boilers now in usc, to aid and assist
in the generation of steam, the water being forced through them by the forcing
pump, and permitted to descharge into the steam chamber of the boiler in lieu
of the steamometer; that the generators may be shielded with fire clay or other
material, to render them more durable and to prevent the destruction of them
by oxydation; that although the steamometer is represented in the Drawing
as set in the same furnace with the generators, it is optional whether_to_have_
it so or otherwise; that the quantity of water injected into the generators may
be regulated by a stopcock placed on the tube leading to the reservoir that
supplies the water, and a cock may also be inserted into the lower side of the
steamometer, to test the fact whether the forcing pump or pumps throw the
proper quantity of water into the generators.
In witness whereof, I, the said John M. Curdy, have hereunto set my
hand and seal, this Twenty-first day of June, in the year of our Lord
One thousand eight hundred and twenty-six.
JNO MCCURDY. (L.s.)

page_text: AND BE IT REMEMBERED, that on the Twenty-first day of June, in the
year of our Lord 1826, the aforesaid John McCurdy came before our said
Lord the King in His Chancery, and acknowledged the Specification aforesaid,
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-first day of June, in the year of our Lord One thou-
sand eight hundred and twenty-six.