AN IMPROVEMENT IN THE STRUCTURE OF CERTAIN BOILERS FOR PRODUCING STEAM FOR THE WORKING OF STEAM ENGINES
Year: 1833

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
MAUDSLAY, of Lambeth, in the County of Surrey, Engineer, send greeting.
WHEREAS His present most Excellent King William the Fourth, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Seventh day of October, in the fourth year of His reign, did, for
Himself, His heirs and successors, give and grant unto me, the said Joseph
Maudslay, His especial licence, full power, sole privilege and authority, that
I, the said Joseph Maudslay, my executors, adññors, and assigns, or such
others as I, the said Joseph Maudslay, 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 "AN IMPROVEMENT IN THE STRUCTURE OF CERTAIN
BOILERS FOR PRODUCING STEAM FOR THE WORKING OF STEAM ENGINES;" in which
said Letters Patent is contained a proviso that I, the said Joseph Maudslay,
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 His 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 Joseph
Maudslay, do hereby declare that the nature of my said Invention, and the

page_text: manner in which the same is to be performed, is described and ascertained in
manner following (that is to say):—
My said improvement is particularly applicable to boilers for steam vessels
which are required to navigate shallow water, and to draw but a small depth
of water, in which case lightness and compactness in the boiler are very
desirable qualities. By virtue of my improvement, efficient boilers may be
constructed for such vessels, occupying less space, and being of less weight
than the boilers usually employed on board steam vessels. My said improve-
ment is also applicable to boilers for locomotive engines, and will form a sub-
stitute for the small internal tubes which are used for horizontal flue passages
through the boilers of the locomotive engines hitherto employed on the Liver-
pool and Manchester Railway, and which small tubes, by their rapid destruc-
tion, occasion great expense and loss of work in repairing.
My said improvement consists in substituting for those small tubes a number
of pairs of cylinders of metal plates of different diameters, placed horizontally
one within the other, but a little excentrically to each other, leaving annular
intervals between them, which intervals form water spaces and flue passages,
disposed in alternate succession one within another, so as to subject the
contained water very effectually to the action of the heat which is passing
through the flue passages, that is to say: the two adjacent cylinders which
constitute each pair are united together at their ends, all round their circum-
ferences, in order that the annular cylindrical space between the two cylinders
of each pair may form a receptacle to contain water, and a suitable number
of such pairs of united cylinders are placed one within the other, but a little
excentrically to each other, leaving intermediate annular cylindrical spaces
between all the several pairs of cylinders, which last-mentioned spaces are left
open at both ends in order to form passages or flues for the current of flame,
heated gas, and smoke proceeding from the fire which is contained in the
furnace or fire-place, and which current passes horizontally through those flue
passages from the fire-place towards the foot of the vertical chimney, and
communicates heat during its course through the said flue passages to the
water which is included in the space between each of the said pairs of cylinders.
The furnace or fire-place may be constructed nearly in the same manner as is
usual in the boilers of the modern locomotive engines, the fire being made
within a fire box, which is surrounded at the sides and over the top with water
contained in an outer case to the fire box, nearly corresponding therewith in
shape, so as to diffuse the water in a thin layer around the fire box containing
the fire.
My said improvement is applicable in lieu of small tubes, to form the flue

page_text: passages from such a fire box, which may be made in any of the forms
hitherto used for the internal furnaces in locomotive or steam-boat boilers.
The aforesaid series of pairs of united cylinders being placed a little excen-
trically one within the other, are to be applied with their axes horizontally (or
nearly so), and presenting their closed or united ends to the back part of the
fire box above the burning fuel which it contains; their opposite, closed, or
united ends, reaching into the space beneath the bottom of the vertical
chimney, in order that the aforesaid flue passages which are left open between
the several pairs of united cylinders may convey the flame, heated gas, and
smoke from the fire to the chimney, and in so conveying may communicate
heat to the water included within the several pairs of united cylinders. The
external and largest cylinder of the series will be similar to the outermost
cylinder of the ordinary locomotive boilers, and will join at one end all round
its circumference to the outer case, which retains the water and steam around
the fire box. The second or next smaller cylinder within the outermost one
will be joined at both ends all round the circumference to the corresponding
ends of the larger outer cylinder, leaving an annular cylindrical space between
the two outermost cylinders to contain water and steam; wherefore the said
two outermost cylinders so united form one pair. Within the said second
cylinder an united pair, consisting of the third and fourth cylinders, are placed
within the second, and a little excentrically thereto; the said pair being united
together all around the circumferences at each end to make the annular cylin-
drical space between them a receptacle for water; the interval between the
second and third cylinders is left open at each end to form a part of the
flue passage, through which the flame, heated gas, and smoke proceeding from
the fire is conveyed to the chimney, and during that conveyance heat is com-
municated to the water included between the outermost pair of cylinders, that
is, between the outer case and the second cylinder, and likewise heat is com-
municated to the water included between the third and fourth cylinders which,
as before stated, are united in a pair within the fourth cylinder; another united
pair, consisting of the fifth and sixth cylinders, are placed a little excentrically to
the fourth, the pair being united together all around each end to form a rescep-
tacle for water, and the interval between the fourth and fifth cylinders is left
open at each end to form another part of the passage for the smoke, flame,
and heated gas, which in their course to the chimney give heat to the water
included between the third and fourth, as well as between the fifth and sixth
cylinders, and so on for as many more pairs of united cylinders as may be
provided to contain water, and disposed a little excentrically, one within the
other, in order to leave open intervals for flue passages between each pair until

page_text: the whole interior of the cylinders is occupied, the innermost cylinder being
closed at each end to form a receptacle for water without having any interior
flue passage within it.
An essential part of my said improvement is to establish a very free circula-
tion of the included water throughout all the several water receptacles aforc-
said, by means of large openings, which are made in the upper sides of all
the several cylinders, one opening exactly over the other, and extending from
the outermost to the innermost cylinder; so that the series of openings will
form a man-hole or entrance from the top of the boiler downwards into the
interior of every cylinder of the whole series, and consequently into the water
spaces between every pair of cylinders which are united, thereby connecting
all the said water spaces together into one, and in the intervals which are
left open for flue passages between the several pairs of united cylinders, the
borders of all the said man-hole openings are filled up all round by filling
rings of metal interposed between the several pairs, and securely rivetted or
screwed through the plate of both those adjacent cylinders between which
each filling ring is interposed. The said filling rings prevent the escape of
water or steam from any of the water receptacles into any of the flue passages
between the pairs of cylinders. The uppermost of the said man-hole openings,
viz, that in the outermost cylinder, is surmounted by a steam head or chest,
rising up to a sufficient height above the boiler to receive and collect the
supply of steam to the engine, so as to avoid a tendency to boil over, and in
the top of the steam chest is a man-hole cover for occasional entrance into the
boiler. The communications which are established between the different pairs
of united cylinders by means of the said man-hole openings will allow the
water to distribute itself freely from one water space to another throughout
the whole interior capacity of such spaces, and will also allow the steam which
is generated within the several water spaces to ascend through the several
man-hole openings to the steam head or chest which is over them, and, if
necessary, two or more sets of man-hole openings, of the kind above described,
may be made at different parts of the length of the series of pairs of cylinders
on their upper sides, each such set of openings communicating from one
pair of cylinders to another throughout the whole series in order to afford
ample passages for the circulation of water and the extrication of steam
therefrom.
In a boiler which is constructed according to my said improvement, the
water which it contains in its several receptacles or spaces between the pairs of
united cylinders will be disposed in a number of thin cylindrical layers situated
one within another, a little excentrically, but all communicating readily one'

page_text: within another, and the heat which passes away from the fire box will be
effectually applied to the contained water by passing along the flue passages or
intervals between those layers. The mode berein-before described of com-
bining the several cylinders into pairs, and combining those pairs together, will
permit the spaces for water and the intermediate flue passages between those
spaces, to be made much narrower than the water spaces and flue passages
can be made in ordinary steam-boat boilers; wherefore, a boiler constructed
according to my said improvement will be lighter, by containing a smaller
quantity of water in proportion to the surface exposed for heating the con-
tained water than can be expected in ordinary steam-boat boilers; also by the
narrowness of the flue passages the boiler will occupy less space on board a
vessel, at the same time that the heating surface which is exposed is rendered
very efficacious by the complete application of the heat in the flue passages,
and by the ready circulation of the water and steam through all the water
spaces.
The interior or central cylinder of the series is to contain water, as before
mentioned, and should be rather longer than the other cylinders, so as to project
Cat a very little beyond the external plate which forms the far end of the outer
case of the boiler under the chimney, and a mud hole door may be provided in
the extreme end of the said central cylinder in order that the interior of that
cylinder may be cleared from all accumulation of dirt which the water may
deposit therein; such deposit is expected to collect principally in the prolonged
end of the said central cylinder, because the circulation of water will be less
complete therein than within the water spaces between the pairs of cylinders;
wherefore the agitation of the water will be less, and consequently the tendency
to deposition will be greater.
To facilitate the repairing of the junctions around the ends of each of the pairs
of cylinders (and by which junctions they are united together to form the water
spaces), each pair of united cylinders may be made a little longer than the pair
within which it is situated, the innermost pairs being the longest, and the
outermost (which is the external body of the boiler) being the shortest, the
central cylinder being longer than any other; wherefore cach junction will
project out so much beyond the others which surround it as is necessary to
give access to the rivetts or screws by which the ends of the several cylinders
are united into pairs.
The supply of water for feeding the boiler may be introduced into the
central cylinder at the far end thereof, and also through branches fro:n one
main feeding pipe to join to each of the several water spaces between the pairs
of cylinders at the lowest parts of the farther end of each pair.

page_text: And for the more complete explanation of my said improvement, I have
hereunto annexed a Drawing which represents a boiler constructed according
thereto. The directions in which the several views are taken are explained by
the titles which are written over each Figure, and the same letters and
characters are used for reference to the same parts in all the Figures.
A, A, is the fire grate; B, B, the internal fire-place or furnace surrounded
with water, which is, contained in the external fire box C, C; D is the fire
door; E, E, is the outermost cylinder forming the body of the boiler; it is
joined to the back of the external fire box C, C, at one end, and the other end
is joined to the smoke box F, F, which is at the bottom or root of the perpen-
dicular chimney G; H, H, is the steam chest fixed on the top of the outer-
most cylinder E, E, of the boiler. g is the horizontal branch of the feeding
pipe, which joins to the lowest part of the boiler at its farthest end to supply
water thereto from a feeding pump; b is a pipe communicating between the
lower part of the external cylinder of the boiler and the lower part of the fire
box, in order to convey water freely from one to the other; and d is a pipe
communicating from the upper part of the fire box to the steam head H, to
convey the steam which is generated around the fire box. e is the safety valve
applied within a pipe which proceeds from the upper part of the steam chest,
and the waste steam which issues is conducted by the waste pipe x into the
chimney G. Thus far the general arrangement is nearly the same as in the
boilers heretofore used in locomotive engines, whereof the construction is
commonly known and requires no further explanation. ff, is an inner cylinder
joined all round its two ends to the two ends of the outermost cylinder E, E,
of the boiler, in order to form an annular cylindrical space for water. The
current of flame, smoke, and heated gas proceeding from the fire in the fire
box passing in contact with the internal surface of the cylinder f. f. gives
heat to the thin layer of water which is diffused around that cylinder in the
said annular cylindrical space; and note, thus far the said boiler does not
materially differ (except in its proportions) from boilers hitherto made with
one large internal tubular flue proceeding horizontally through the cylindrical
body of the boiler from the fire box to the chimney; but my improvement
consists in applying within such large internal tubular flue a series of pairs of
united cylinders disposed one within another, containing water in the spaces
between the two cylinders which constituite each pair, and leaving open inter-
vals for flue, passages between the successive pairs of cylinders, and in uniting
all the several water spaces of the said pairs into one common receptacle, by
means of the series of man-hole openings which descend into the same from
the steam head, as before mentioned, and in making each of the innermost

page_text: pairs of cylinders longer than the pair within which it is situated, in order that
the junctions of the several cylinders may be accessible for examination and
repairing. These particulars of my improvement are designated in the Drawing
by the numeral characters as follows:-1, 1, 2, 2, 3, 8, are three pairs of united
cylinders containing water between them; and 4, 4, is the central cylinder
containing water; 5, 6, 7, and 8, are the series of man-hole openings into the
upper part of each of the said pairs of cylinders, those openings being one
beneath another, so as to penetrate down into all the several water spaces by
one common entrance, which allows a free passage of water and steam from
one to another. The vertical section shows the filling rings, which are inter-
posed between each of the pairs of cylinders around the borders of their
respective man-hole openings 5, 6, 7, and 8, and the horizontal plan 'shews
the form and size of the said openings, each one being smaller and more.
oblong or oval than the one above it, by which means the rivets or screws by
which the said borders and filling rings. are united are left accessible for
examination and repairing.
The filling rings are situated in the spaces or intervals which are left for flue
passages between the pairs of cylinders, and owing to the pairs of cylinders being
placed a little. excentrically one within the other (as before mentioned), the
spaces left for flue passages are wider at the lower part and narrower at the upper
part of each annular space; wherefore the heat will be rendered most operative
at the lowest parts, and the thickness of the filling rings 5, 6, 7, and 8 will be less
than would otherwise be requisite. The man-hole opening in the inner cylinder of
cach pair of united cylinders is smaller and more oblong or oval than the corre-
sponding opening in the outer cylinder of the same pair; 9, 9, 9, 9, are branches
from the common feeding pipe n to the several water spaces, and to the central
cylinder, to supply every space with water; r is a blow cock at the bottom of
the common feeding pipe n, to allow the water in the boiler to be discharged
when required for cleansing; s is a moveable cap at the end of the central
cylinder 4, to permit of cleaning out any mud or sediment which may deposit
therein. The several pairs of united cylinders.are retained in their respective
places one within the other, by connecting braces at each end, extending from
the central cylinder across the ends of all the others, and fastened to them as
shewn in the transverse section; and note, in order to give adequate strength
to a boiler constructed according to my said improvement, the inner and
outer fire boxes, and also the two cylinders of which each pair of united
cylinders is composed, may be united together by screwed bolt stays inserted
from the outer to the inner cylinder, such stays being disposed at suitable
distances apart, and applied, screwed, and rivetted fast in the manner usually