IMPROVEMENTS IN STEAM BOILERS
Year: 1844

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
JOHNSTON, of Willow Park, Greenock, Esquire, 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 Eighth day of February, in the seventh year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said James
Johnston, Her especial licence, full power, sole privilege and authority, that I,
the said James Johnston, my exors, adiñors, and assigns, or such others as I,
the said James Johnston, 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, my
Invention of "IMPROVEMENTS IN STEAM BOILERS;" in which said Letters Patent
is contained a proviso that I, the said James Johnston, 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 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
James Johnston, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are fully described and

page_text: ascertained in and by the following statement thereof, reference being had to
the Drawings hereunto annexed, and to the figures and letters marked thereon
(that is to say):
The improvements in boilers which I claim as new and original have
reference to that part of boilers called the furnace. My improved furnace is
constructed in accordance with the principles on which the boilers are con-
structed for which I obtained a Patent on the Twentieth day of April, One
thousand eight hundred and forty-three. Before describing the improved
furnace, I shall first give a further explanation of those principles on which
both the body of the boiler and the furnace are constructed.
EXPLANATION.
Figure 1 represents a perpendicular section cut through the body of a boiler.
A, B, is the water line. All the area of the boiler below that line is filled with
water, except the flues C, D, C, D, C, D, &c., &c. The Figure shews an end
view of those flues, taken across them, so as to be able to look through the
flues from the front to the back of the boiler. Those flues are made of plates
of metal, and owing to their sides being flat the water spaces between them
are in the form of flat plates or sheets, which I call sheet-water spaces.
Owing to there being no flues passing through the large water spaces
E, F, E, F, which are at the sides of the boiler, the water in those spaces is in
the state that engineers term solid, in contradistinction to water that is in the
act of being converted into steam. (In a boiler which I have lately made
I have further improved the current of water by filling up the two extreme
side flues with fire-clay, so that no heat whatever can pass directly from the
fire or flues to the descending water spaces E, F, E, F.) For explanation sake,
I shall suppose a boiler like the one described to be working at a pressure of
ten pounds on the square inch. Now when water is converted into steam
under this pressure, each cubic inch of water produces or is converted into one
thousand and eighty-four cubic inches of steam. Each cubic inch of steam
must therefore be one thousand and eighty-four times lighter than a cubic
inch of water, as steam is merely the particles of water expanded by heat, and
heat has no weight. In the boiler we have the descending water spaces E, F,
E, F, in which the water is always solid; and we have the narrow water spaces
between the flues, in which the water is in the act of being converted into
steam. The natural result is, that whenever a particle of steam is formed in
any of the sheet-water spaces the water in the spaces E, F, E, F, immediately
rushes down and displaces the steam, as the solid water is one thousand and
eighty-four times heavier than the steam.
It is this natural result consequent

page_text: nues, and, further, it insures a uniform and steady action of the bone.
improved furnace is applicable to all kinds of boilers, and may be used
either with or without my patent boiler.
DESCRIPTION OF THE FURNACE.
The furnace of the common locomotive boiler consists of two principal parts,
videlicet: the casings, called the inner and outer fire-boxes. Those fire-boxes at
their sides are connected together with bolts, in order to prevent the steam
forcing them asunder. The roof of the internal fire-box is supported by
wrought-iron ribs, which are bolted to it, and prevent its yielding to the
pressure. In my improved furnace the fire-boxes are bolted together, not only
at the sides but also at the roof. The objections which might be urged against
this plan are as follows:-First, a deposit of sediment would occur on the roof
of the internal fire-box, which could not be removed, as no access can be had
between the closely-bolted roofs; second, there would be a liability of the
steam accumulating between the inner and outer roof of the furnace, and
forcing the water out so that the internal roof might be destroyed. I obviate
these objections by causing a current of water to flow up the sides and over
and along the inner roof of the furnace. The advantages gained by this form
of furnace are great strength and lightness. Lightness is attained in conse-
quence of the practicability of making the water spaces around the furnace of
less than a sixth of their present bredth. This I have ascertained can be done
with perfect safety.
DESCRIPTION OF THE DRAWINGS.
Figures 2, 3, and 4 are plans of my improved furnace, so arranged that it
might be applied to any boiler having internal flues.
Figure 2 is a side view of it. A, B, C, D, is the body of the furnace;
E, F, is one of the conductors for conveying water from the boiler to supply
the water space at one of the sides of the furnace; G, H, is the conductor for
conveying the steam and water from the furnace to the interior of the boiler.
Figure 3 is a section of the furnace taken through the dotted line Figure 2.
L is the fire-bars; E, F, E, F, are the two conductors which convey the
water from the boiler to the water spaces of the furnace; G, H, is the steam
and water conductor; m, m, m, m, &c. are the bolts which fasten the inner
and outer fire-boxes together.

page_text: Figure 4 is a view of the end of the furnace, exhibiting the way in which
it is intended to fasten it to the boiler B, D, B, D. The ends of the two sides
of the furnace are closed up by having a piece of metal of the breadth of the
water space rivetted between the plates. The water conductors, E, F, E, F,
and the conductor G, II, have flanches fastened round their ends, which are
perforated with holes, so that they can be rivetted or screwed to the front of a
boiler in which there has previously been made openings to correspond with
the mouths of the conductors. In constructing a furnace after this plan, the
conductors E, F, at their mouths, where they join the boiler, the area of each
should be equal to or larger than the area of a horizontal section of the water
space which they are intended to supply. The area of the conductor G, H,
should be equal to or larger than the joint area of the conductors E, F, E, F.
I do not confine myself to the plan of furnace herein described, in so far that
the shape of it may be very much varied, and yet it may work in accordance
with the improvements which I have invented. The more perpendicular the
sides of the furnace are the better will it work. The top of the furnace
may be of any shape, always keeping in view that it should be so constructed
that one part of it is higher than the rest, and that all the other parts of it
slope up to the highest point, so that the current of water and steam rises
gradually to the highest point, and from thence are conducted into the boiler.
The furnace, as drawn in the plans, has no water-space under the ash pit. In
some boilers this will be necessary; and, in the event of its being required, I
intend that the bottoms of the inner and outer fire-boxes should be fastened
together like the other parts of the furnace. If more than one furnace be
required to a boiler, furnaces according to my improved plan can be placed
adjoining one another. One water-space may then be made to serve as a par-
tition between two furnaces. The furnace which I have just described might
of itself be easily made to answer the purpose of a boiler, if the conductors
E, F, E, F, and G, H, were united, or made to communicate together with
pipes, or any other convenient apparatus, so that the surplus water from G, H,
be returned, and enter E, F, E, F; the water would then continne to flow up
the sides of the furnace, and over and along the top of it, and then down the
pipes or other apparatus for the purpose. Thus it would answer the purpose
of a boiler if the other necessary accompanyments of a boiler were added to it.
This shews how my improved furnace can be converted from a furnace into a
furnace boiler.
I claim as new and original the making and using of boiler furnaces and
furnace boilers of which the inner and outer fire-boxes are bolted together at
the roof as well as at the sides, conjointly with the constructing the said furnace

page_text: or furnace boiler so that (when the fire is burning) a current of water is made
to ascend up the sides and over and along the top of the inner fire-box. In
other words, I claim as new and original the constructing the furnaces of
boilers of sheet-water spaces, conjointly with there being currents of water
created in the said water-spaces, in accordance with the principles explained in
this Specification.
In witness whereof, I, the said James Johnston, have hereunto set my
band and seal, this Eighth day of July, in the year of our Lord One
thousand eight hundred and forty-four.
Enrolled the Twenty-sixth day of July, in the year of our Lord One
thousand eight hundred and forty-four.