CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF BOILERS FOR GENERATING STEAM
Year: 1851

page_text: MILLIGAN'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EMERY MILLIGAN, Mechanical Engineer, of the City of New York, United
States of America, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Nineteenth day of
December, One thousand eight hundred and fifty-one, in the fifteenth year of
Her reign, did for Herself, Her heirs and successors, give and grant unto
me, the said William Emery Milligan, my exors, admiors, and assigns, Her
especial license, full power, sole privilege and authority, that I, the said
William Emery Milligan, my exors, adñiors, and assigns, or such others as I,
the said William Emery Milligan, my exors, adñiors, 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, in the Islands of Jersey, Guernsey, Alderney, Sark, and Man, and in
all Her Majesty's Colonies and Plantations abroad, my Invention of "CERTAIN
IMPROVEMENTS IN THE CONSTRUCTION OF BOILERS FOR GENERATING STEAM;" in which
said Letters Patent is contained a proviso that I, the said William Emery
Milligan, shall cause a particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, by an instrument in
writing under my hand and seal, to be inrolled in Her Majesty's High Court
of Chancery within six calendar months next and immediately 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.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William Emery Milligan, do hereby declare that the nature of my said Inven-
tion, and the manner in which the same is to be performed, are fully described
and ascertained in and by the present Specification thereof, reference being
had to the Drawings hereunto annexed, that is to say :-
The nature of my Invention consists of a new arrangement of flues, tubes,
and water spaces within a boiler for generating steam, whereby a much larger
amount of surface is exposed to the action of heat than usual.
In its general
external appearance this improved boiler is similar to ordinary boilers, neither
does it differ materially from others in regard to the construction of the enclosed
furnace (considered by itself.) but upon the other side of the fire-place (a) are
placed a series of flues (b, b.) Figure 1, of a number and capacity sufficient to
carry off readily the products of combustion from the furnace. These flues
open into a horizontal flue (c), which is placed above the furnace and below
the water line of the boiler. At the back of the furnace (a), and near to the
bottom of the boiler, there is another horizontal flue d, and between the two
horizontal flues there is a series of vertical flues similar to the flues (6), but
necessarily longer, as shown at (c), and these latter flues are for the purpose
of conveying the products of combustion from the upper to the lower horizontal
flue. Through the centre of each of the vertical flues (e) I introduce a tube (f),
say of one half the diameter of the flue, which tubes extend from the upper
tube sheet of the horizontal flue (c) through the lower tube sheet of the flue (d),
as shown. The water passes through these tubes, which serve the purpose not
only of presenting greater surface for the absorption of heat, but ensure the
circulation of the water within the boiler. From the lower horizontal flue (d)
the products of combustion are conveyed into the chimney by means of the
flues (), as shown; one, two, or more furnaces provided with flues and tubes
thus constructed and arranged may be placed within the same shell, sufficient
space being left between them, as shewn, for the circulation of the water.
The practical result of this improved system is as follows: The water in the
boiler rising above the upper horizontal flue fills the tubes (f, f), and sur-
rounds all the flues. The products of combustion pass from the flue (c),
through the vertical flues (c, c), parting with their heat on the one side to the
immediately surrounding water, and on the other to the water within the
tubes (ff). The water contained in the tubes is much more rapidly heated
than that surrounding the flues, as its volume is less; and hence, by known laws,
a regular and perfect circulation takes place within the boiler.
The flues (c) and (d) may be placed vertically, and the others horizontally,
or vice versa; and though preferring the disposition of the parts represented in

page_text: the Drawings, I do not restrict myself to it, but claim generally the arrange-
ment of the tubes and flues in such manner that the water tubes shall be
connected with an upper and lower tube sheet, in combination with flues of less
length than the tubes, as also the connecting of the said tubes with an upper and
lower flue sheet, whereby two horizontal flues are formed in such connection with
cach other, by means of vertical flues, that the products of combustion from the
fire-place shall pass into the upper horizontal flue, and thence down the vertical
flues into the lower horizontal flue, parting with their heat on the one hand by
radiation through the flues to the immediately surrounding water spaces, and
on the other through the tubes to the water circulating through them all, as
before exemplified and described.
In witness whereof, I, the said William Emery Milligan, have hereunto
set my hand and seal, this Eighth day of April, in the year of our Lord
One thousand eight hundred and fifty-two.