IMPROVEMENTS IN MARINE STEAM BOILERS, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER STEAM BOILERS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1861

page_text: LETTERS PATENT to Robert Armstrong, of North Woolwich, in the
County of Essex, Civil Engineer, for the Invention of "IMPROVEMENTS IN
MARINE STEAM BOILERS, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO
OTHER STEAM BOILERS, AND IN APPARATUS CONNECTED THEREWITH."
Sealed the 6th December 1861, and dated the 10th June 1861.
PROVISIONAL SPECIFICATION left by the said Robert Armstrong at the
Office of the Commissioners of Patents, with his Petition, on the 10th
June 1861.
I, ROBERT ABMSTRONG, of North Woolwich, in the County of Essex, Civil
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-;
MENTS IN MARINE STEAM BOILERS, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE
TO OTHER STEAM BOILERS, AND IN APPARATUS CONNECTED THEREWITH," to be as
follows:-
1. The first of my said improvements is for the purpose of preventing the
priming of the water of the boiler into the cylinder of the steam engine. It
is more particularly applicable to boilers of the vertical class and those having.
circular outside shells. It consists in placing a perforated shelf or bracket..
which I call a "priming shelf," projecting from the interior sides of the shell.
a few inches below the surface level of the water, and extending over the
width of the water spaces between the flues, or between the flues and the

page_text: shell. This priming shelf is to be carried all round, or nearly all round the
interior of the boiler, and to be constructed in removable portions so as to
admit of easy access to workmen.
2. The second of my said improvements is for a similar purpose to the first,
and consists of a series of scum pans of an improved description, having
serrated or vandyked edges, and made adjustable to any variation of the
water level by means of a screwed rod or shaft passing through a stuffing
box, and which may be actuated by a handle outside the boiler.
3. The third of my said improvements is for the purpose of promoting the
circulation of the water, in connection with a mud receiver, so placed, either
externally or internally, or below the ash-pit of the boiler, that the circulating
current holding any insoluble matters in suspension, may generally pass over
and deposit such insoluble matters therein. A pipe of communication, pro-
vided with proper stop-cocks or valves, between any of the scum pans and the
receiver, enables both to be blown out at the same time.
4. For the prevention of calcareous scale, I make use of staves of oak or
any other wood yielding tan or other extractive matter that readily combines
with lime. The peculiar arrangement of these wooden staves, which staves
may be cut square or flat, or in any convenient shape, and which I call
"scale preventers," forming a kind of lagging, sheathing, or lining inside the
boiler shell, that I use for this purpose, is that of supporting them in a rack
similar to the old fashioned plate or delf-rack of a kitchen, but carried entirely
around the interior of the shell or wall of the water chamber, and is the most
convenient for removing, replacing, or renewing these "scale preventers."
5. In order to combine the aforesaid improved apparatus in one compact
form of boiler, or series of boilers of the greatest strength and portability, I
proceed in the following manner:-I take two cylindrical boilers of the
vertical class, having vertical fire boxes or combustion chambers within them,
and attach them together by means of one or more suitable channels or flues
connected to the upper parts of their respective fire boxes, but below the
surface level of the water, and passing through the outer water space, namely,
that between the fire box and the shell of the boiler. A fire being placed on
a suitable grate within or below the fire box of one of these boilers, which I
designate as "No. 1 boiler" or compartment, the flame and hot air proceeding
therefrom will of course rise to the top of the fire box, thence through the
aforesaid channels or passages into the next, which I call "No. 2 boiler,"
within which the flame descends downwards, and passes out thereof by a
suitable passage at, near to, or below the bottom of this No. 2 boiler to the
chimney. This simple arrangement of two vertical cylindrical compartments

page_text: is in many cases all that is essential to constitute what I call my "double
upright" or compound boiler, when not very large, and intended to work at a
moderate pressure. When, however, a boiler of great power is required to
work at a very high pressure, and with great economy in fuel, then instead of
passing the flame and hot air direct into the chimney from No. 2 compart-
ment, they are to be directed into another nearly similar compartment or
boiler, which I call No. 3; this No. 3 boiler differs from No. 1 and 2 prin-
cipally in having a larger proportion of water space, and being surmounted by
a short funnel passing through the steam chamber and the top of the boiler,
or it may be connected with a chimney in any other manner.
This No. 3.
boiler may also contain a small grate upon which a temporary fire can be
kindled for the purpose of "starting" the draught when the steam is to bo
first raised.
6. My next improvement in the construction of these boilers, has for its
object still further to increase their strength, and thereby their available power
for a given weight of metal, and also for increasing the most effective heating
surface, and thereby the economy of fuel. For this purpose I apply to the
fire-boxes and combustion chambers of these improved boilers, or to any other
description of boiler in which steam is to be generated within tubes, and I fix
therein two or more tubular stays or pipes of a peculiar form and arrange-
ment, extending across horizontally, or nearly so, from side to side of the fire-
box, fire flue, or combustion chamber, and when they admit of being arranged
in pairs, I recommend such tubular stays to be crossed over each other at, or
about at right angles, or in any convenient manner that will expose tho
largest possible surface to the upward action of the flame. The ends of these
tubular stays, where they are attached to the sides of the fire-box, and through
which the water of the boiler is to circulate, are to be made oval or elliptical,
with their transverse or longer diameters vertical, in order to give easier
admission for the circulating water into the lower, and an easier exit to the'
generated steam out of the upper part of the tube. These two points being
equally essential to the durability of the tube and the rapid generation of
steam, as well as being necessary for the expulsion of all sediment from the
interior of the tube. The middle portion of the tube is also to be made
elliptical in cross section, but with the longer axis of the ellipse in the
contrary direction, that is, horizontal instead of vertical. The reason of this
is, that a greater number of tubes of equal area can then be placed crossing
each other in the same height of fire-box, or in the same length of flue.
These tubes, which I call "steam and water tubular stays," are alike appli-
cable for supporting the pressure upon the internal flues and fire-boxes of the

page_text: Cornish and other kinds of horizontal as well as vertical boilers, and also to
ordinary marine boilers, for which they are well adapted for "water-bridges," as
well as in the construction of superheaters, and admit of being fixed in any
position.
7. In order to superheat and dry the steam, I fix a series of the cross
tubular stays above described in pairs within the funnel, the lower part of
which is enlarged for that purpose, which part is also to be surrounded by a
double casing or "jacket," consisting of a series of semicircular or segmental
cells, each cell connecting the ends of a pair of tubes on each side of the
funnel alternately in such manner that the steain being first conveyed to the
uppermost tier or pairs of cells and tubes, is then caused to descend through
the cells and across the funnel, tier after tier, through successive pairs of tubes,
until arriving at the root, or hottest part of the funnel; this superheated
steam is then drawn off to the cylinder of the engine.
8. My next improvement is for heating and purifying the feed water of
steam boilers, and is applied to the above described compound vertical boiler
in the following manner:-A cast-iron, or partly cast-iron tank of suitable
form and dimensions with a closed top, though in communication with the
atmosphere by means of an open safety pipe, and kept always full of water, is
to be placed as a foundation upon which the middle or No. 2 compartment of
the said compound boiler is to be fixed, in such manner that the descending
flame in that compartment may reverberate upon the top of the tank, thereby
heating the upper surface of the water in contact with the latter, until the
water overflows into a part of the tank partitioned off for the purpose, whence
this heated water is drawn off by the feed-pump, injector, or otherwise, to
supply the boiler, while all sedimentary matters will settle and romain in the
other portion of the tank, to be removed from time to time.
9. The next improvement is for the purpose of preventing the nuisance of
black smoke, and consists in forcibly projecting two or more jets of air
opposite to each other in pairs into the flame within the fire-box of No. 1
boiler, thereby supplying additional oxygen to the interior of the flame, while
the two opposing currents of air may so commingle with each other and with
the flame as to prevent the usual injurious "blowpipe-action" on the material
of the fire-box, and at the same time mix intimately with the combustible
gases, which are thereby inflamed, and the smoke is, as legally termed, " burned
or consumed."
10. The tenth and last improvement is to be used in conjunction with the
ninth for the purpose of further perfecting the combustion of the inflammable
gases arising from the fuel, and is accomplished by having the fire-bars made

page_text: thicker at one end than the other, and placed with their thick and thin ends
side by side with each other alternately, supported by a notch in the thick end
of each bar, over a moveable transverse bearing bar at each end of the grate, in
such manner that moving this bearing bar will effect the widening or narrow.
ing of the spaces between the furnace bars, thereby proinoting either quick or
slow combustion as may be desirable. In order to lessen, and in part super-
sede the labor of the "fireman" in stoking the fire, I form a portion of the
fire-bars with ratchet-formed teeth on their upper faces, so that by a simple
"to-and-fro" movement of the bearing bar, the coals may be advanced for-
ward towards the fire-bridge without opening the fire-door. This movement
of the bars may obviously be made self-acting by a connection with the steam
engine, and when so effected, I call this arrangement the mechanical stoker. .
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Armstrong in the Great Seal Patent Office on the
10th December 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
ARMSTRONG, of North Woolwich, in the County of Essex, Civil Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of June, in the year of our Lord One
thousand eight hundred and sixty-one, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Robert Armstrong, Her special licence that I, the said Robert
Armstrong, my executors, administrators, and assigns, or such others as I, the
said Robert Armstrong, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN MARINE STEAM BOILERS, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE TO OTHER STEAM BOILERS AGD IN APPARATUS CONNECTED THEREWITH,"
upon the condition (amongst others) that I, the said Robert Armstrong, my
executors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within six

page_text: calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Robert Armstrong, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
My Invention relates, firstly, to certain improvements in steam boilers,
principally applicable to those of the vertical kind, having cross water tubes
in their fire-boxes, for which Her Majesty's Patent under the Great Seal
was granted unto me on the Fourteenth of December, One thousand eight
hundred and fifty-eight, No. 1419, of which a general representation is given
in Figure 1 of the annexed Drawing.
Secondly, my Invention relates to a combination of two or more such or
similar boilers placed side by side, and attached to each other by suitable
channels or short flues passing through their outer shells and water spaces,
by which their respective fire-boxes or combustion chambers are connected,
thus forming a duplex or compound vertical boiler of less elevation, though
of equal strength and greater portability, and thereby better adapted to
marine and other locomotive purposes.
Thirdly, it relates to various apparatus and adjuncts applicable to steam
boilers generally. With respect to the single vertical boiler above referred
to, in order to prevent the "priming" of the water of the boiler into the
cylinder of the engine, I fix therein near the surface level of the water a
perforated circular shelf or continuous bracket, which I call a "priming
shelf," projecting from the interior side of the shell of the boiler and extending
over the width of the water spaces between the shell and the fire-box. This
priming shelf is to be continued around or nearly all around the circumference
of the interior of the boiler, and constructed in removable portions or segments
in the manner represented in section and plan at A, B, and A', B', Figures 1
and 2 respectively. For the still further and more complete prevention of
priming, by purifying the feed water, and also for heating the same, I use
a cast-iron box or tank, which serves as a foundation for the boiler to stand
upon, and is to be divided into two unequal divisions by a partition across its
interior reaching to within half an inch of its cover or lid, which lid is to
be cast with a thick projecting convexity un its under side so as to dip to
at least an inch below the surface of the feed water when the larger division
of the tank is fully charged therewith. The resulting effect is, that the
heat thus communicated to the water is sufficient to cause the latter to
expand at the surface, and gradually pass over the top of the partition from

page_text: the larger to the smaller division of the tank. From which division the
boiler may be supplied with comparatively clean as well as heated feed water,
while the sedimentary deposits will settle in the larger division to be removed
from time to time. This feed water heater and cleaner is represented in
vertical section and plan at C and D, Figures 1 and 3 respectively.
My next improvement in the aforesaid single vertical boiler, which is
also applicable to all forms of boilers having internal water tubes, is in the
precise form of the tubes themselves, by making the latter oval or elliptical
in cross section in the central portion, and also at the ends of each tube,
while the central portion and the ends have the axes of their respective
ovals at right angles to each other, the longer axis of the central oval being
horizontal, while that of the end oval is vertical, thus forming the strongest
and most durable shape of water tube or tubular stay for a boiler, and which
call my double oval tubular stay. Such stays are represented in section
at E and F, and by the diagram G in Fig. 1, and also in horizontal section
and plan in Figs. 4 and 5 respectively.
With respect to the duplex or "double upright" form of boiler it is to bo
constructed in the following manner :-I first take a single upright cylindrical
boiler, in all respects similar to the single vertical boiler above-described,
but without the funnel or chimney, and also without the feed water heater,
and which I call No. 1 boiler. To this No. I boiler I attach another similar
boiler without any fire-grate, which I call No. 2 boiler, by means of a short
flue or flues in the manner represented in the Drawing in vertical section
Fig. 6, and in horizontal section or half plan Fig. 7. This No. 2 boiler
may be of the same dimensions or nearly so as No. 1, and is to stand upon
one or more tanks or feed cisterns, similar to the aforesaid single boiler,
and their joint operation, when at work, is as follows:-A fire being placed
on the grate of No. 1 boiler, the flame and hot air proceeding therefrom will
of course ascend to the top of the fire-box, and thence through the aforesaid
short connecting flue into the combustion chamber of No. 2 boiler, within
which the flame descends downwards and passes out thereof by one or more
suitable passages to the funnel or chimney.
In some cases instead of passing the proceeds of the combustion direct into
the chimney from No. 2 compartment, they may be directed into another com-
partment or boiler which I call No. 8 boiler, which differs from boilers 1 and 2
principally in having a tapered uptake or funnel passing through the steam
chamber, by which the steam may be, to a certain extent, superheated. This
No. 3 boiler may also be surmounted by an external chimney funnel, sur-
rounded by a double casing or steam jacket, into which the steam may be

page_text: conveyed for the purpose of being further superheated or dried on its way to
the engine.
To the Invention of this mode of superheating the steam I make no claim,
excepting so far as the steam is passed from one side of the said double casing
through the hot smoke in the funnel to the opposite side by means of a series
of hollow cross stays or tubes, similar to the before described double oval
tubular stays, but with this difference only, that these tubes contain steam,
while the others contain water; they generate, while these regenerate or
superheat, the steam.
My next improvement is for the purpose of occasionally avoiding or preventing
the appearance of black smoke at the funnels of steam ships when used for
war, or other purposes, and consists in forcibly projecting two or more jets of
air opposite to each other in pairs into the flame within the fire box, thereby
supplying additional oxygen to the interior of the flame, while the two opposing
streams of air may so commingle with each other and with the flame as to
prevent the otherwise certain injurious "blowpipe-action" of the flame on tho
material of the fire-box, and at the same time mix intimately with the com-
bustible gasses,
which thereby become inflamed, and the smoke is, in legal
parlance "burned or consumed." As in the last clause on superheating, I
lay no present claim to the Invention of this mode of admitting air to furnaces,
although one of the first Inventors thereof previous to 1830; neither do I
recommend this nor any other mode of admitting air above the fuel while the
heat of the smoke is required to superheat the steam. The simultaneous use
of the two processes being, in respect to economy, clearly inconsistent with
each other.
In order to effect the smokeless combustion of bituminous coals economi-
cally, without detriment to the superheating qualities of the boiler funnel, I
recommend a continuous or frequent slight movement of the fuel on the grate,
which I accomplish by having each grate or length of fire-bars supported by
a rocking transverse bearing bar at one end, and an adjustable or regulating
bearing bar at the other. I also make the fire-bars thicker as well as deeper
at one end than the other, and I place these taper fire-bars with their thick
and thin ends side by side with each other alternately, in order that the with-
drawal of the adjustable bearing bar may have the effect of widening the
spaces between the fire-bars, or the converse, thereby promoting either quick
or slow combustion, as may be desirable. At the same time a rapid up-and-
down movement is to be imparted to the other ends of the alternate bars by
means of a hand lever attached to the rocking bearing bar; which operation
will have the effect of shaking and expelling all dust and ashes from the air

page_text: spaces down into the ash-pit. Thus the tendency to flux any siliceous or other
carthy impurities in the fuel, and consequent formation of clinkers, will be
prevented; while at the same time the draught through the grate will be
accelerated, thereby increasing the temperature of the furnace and the effi-
ciency of the boiler. A furnace with these movable fire-bars and apparatus is
fully represented in longitudinal sections F, F1, plan, and cross sections F","
F, in Figures 8, 9, 10, and 11 respectively. a, a, a, is the adjustable
bearing bar, with its connecting rod and handle e, e. The rocking bearing bar
b, b, b, with its rocker and hand lever d, d, d, is shewn in Figs. 8, 9, and 11;
c, c, in Figs. 8 and 9 shew the thick end of a rocking fire-bar in the position:
for being moved; while g, g, shews one of the adjustable fire-bars in the
position for being screwed backward or forward by the regulating handle e, e.
Here I wish to observe that the rocking fire-bars may be worked by a donkey-
engine, or any other prime mover, and that I claim the adjustable taper fire-
bars and apparatus belonging thereto only, and not any particular method of
working the rocking bars..
Another improvement which is also applicable to ordinary marine and other.
boilers in the preventing or greatly mitigating the effects of priming consists
in fixing one or more scum pans of an improved description, having serrated
or vandyked edges very near to the surface of the water within the boiler, in
the manner represented in Fig. 6, by three different modifications of scum pans
at H, I, and K, respectively, especially adapted for vertical boilers, and also
by another modification, as shewn in section at L, and in elevation at L' in
Figs. 8 and 11, more suitable for ordinary horizontal boilers. The scum
pans H and K, in Fig. 6, and also that shewn in Figs. 8 and 11, require to be
permanently fixed with the bottom of their V-shaped notches at about one inch
below the surface of the water; but that shewn at I in Fig. 6 is so made
that it can be adjusted to the surface level of the water at any time while the
boiler is at work, by means of a screwed rod passing through the stuffing box I¹
on the top of the boiler, by turning which the interior or sliding top of the
scum pan [i] can be raised or lowered and adjusted as required. These
scum pans are to be supplied with discharge pipes, cocks, valves, or other
outlets, as at H and 1", Fig. 6, by which the scum is to be blown off from
time to time.
My next improvement is an apparatus for promoting the circulation of the
water and a sediment collector or mud receiver combined. This apparatus is,
for the better explanation of its construction and operation, shewn as detached
from the boiler by Fig. 12; it consists of a vertical pipe or narrow vessel M,
placed in any convenient situation near the side of the boiler as at M' in the

page_text: plan, Fig. 7, and connected thereto by two pipes with stop-cocks or valves at
N and O, through which, when open, the water circulates in the direction of
the arrows, and any sedimentary matters held in suspension will be gradually
deposited at the bottom of the box P, and may be at any time discharged at
the blow-off cock P', after being stirred up with the agitator [9] by means of
its shaft and handle Q. In order to clear the surface of the water of all
floating sediment, and thereby do away with the principle cause of priming,
the two cocks N and O must be occasionally shut off, and the mud receiver
emptied; immediately after which, and while the blow-off cock is still open,
the top cock N, which is in communication with one of the scum pans, must
also be suddenly opened, when the surface of the water will be instantly
skimmed of all floating substances whatever.
For the prevention of calcareous incrustations I make use of strips or staves.
of young oak wood, two or three inches thick by 3 or 4 feet long, which
I suspend around the interior of the boiler by attaching one end of each stave
And in horizontal boilers
to the priming shelf herein-before described.
I place these staves horizontally on racks fixed to the shell of the boiler in
such manner as to be easily removed and replaced by fresh ones every 3 or 4
months.
In witness whereof, I, the said Robert Armstrong, have heretofore set
my hand and seal, this Tenth day of December, One thousand eight
hundred and sixty-one.
ROBERT ARMSTRONG. (L.S.)
ROBERT ARMSTRONG. (L.S.)