IMPROVEMENTS IN THE CONSTRUCTION OF STEAM BOILERS, AND IN APPARATUS TO BE USED IN THE MANUFACTURE THEREOF
Year: 1876

page_text: LETTERS PATENT to Bristow Hunt, of Serle Street, Lincoln's Inn, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS IN
THE CONSTRUCTION OF STEAM BOILERS, AND IN APPARATUS TO BE USED IN
THE MANUFACTURE THEREOF." A communication from abroad by Alvan
Dinsmore Brock, Engineer, of Washington, District of Columbia, in the
United States of America.
Sealed the 2nd February 1877, and dated the 2nd August 1876.
PROVISIONAL SPECIFICATION left by the said Bristow Hunt at the Office
of the Commissioners of Patents on the 2nd August 1876.
BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM BOILERS, AND IN
APPARATUS TO BE USED IN THE MANUFACTURE THEREOF." A communication from
abroad by Alvan Dinsmore Brock, Engineer, of Washington, District of Columbia,
in the United States of America.
The objects of and the advantages intended to be attained by this Invention are
as follows:
First. The production of steam at any desired pressure for locomotive or marine
propulsion, or for other useful purposes, and with a degree of safety from dangerous
explosions not attained in any other known boiler.
Second. Constructing and arranging the water tube henting surfaces in such a
manner that a remarkable increase in the amount of such surfaces is exposed to the
action of the products of combustion as compared with other boilers, and at the
same time reducing the weight and bulk in a proportional degree.
Third. The disposition and arrangement of the heating surfaces in such a manner
as to produce the greatest possible effectiveness from the products of combustion.
Fourth. The construction and arrangement of the coils of water tubes for steam
generators in such a manner that great economy of labour is secured.
Fifth. The attainment of a constant, effective, and natural circulation of water
through these tubes, whereby danger of overheating is avoided, and the formation
of scale or sediment on the inside surfaces is prevented.
Sixth. The peculiar connection and combination of a series of coils of water
tubes so that each one of the series shall have an independent connection with the
general circulatory system, and so that each coil can, if desired, be readily detached
and replaced without disturbing the others of the series.
[Price 8d.1

page_text: Seventh. The construction of the steam and water reservoir of water tube boilers
in sections, each of which shall be of comparatively small diameter, and yet so
combined and connected that the water and steam may freely circulate through
them, allowing the water to stand at the same level in them all, while at the
same tinie contributing materially to the steam producing capacity and capable of 5
standing almost unlimited pressures (the latter of course depending of course upon
the diameter of the sections).
Eighth. The peculiar combination of the water tube coils and the reservoir
sections, by which means extraordinary steam generating capacity is united to a
corresponding ability to withstand very high pressures, and also, should a rupture 1
occur in any one of the sections of the coils or of the reservoir the strain upon the
remaining ones would be gradually relieved.
Ninth. The attainment of extreme portability, inasmuch as all the sections of
water tubes and of the reservoir may be so reduced in size and weight that very
large generators may be transported in separate sections to positions and places ]
utterly inaccessible to boilers of the ordinary type.
Teuth. The attainment of a much greater temperature in the boiler furnace than
is now practicable through the perfect circulation of the water in the sections.
Eleventh. Reducing the grate surface and increasing the intensity of combustion,
as well as the amount of heating surface, at the same time that the effectiveness of
the latter is also largely increased.
And, Twelfth. The construction of the sections of water tube boilers in inter-
changeable parts, after the so-called "assembling" system, wherein each and every
part is made to a certain determined scale, and can be at once applied to any boiler
of that size and type, and whereby any required number of parts likely to be
required under ordinary circumstances can be kept in stock for emergencies.
The Invention consists in the following manner of construction, which is the one
preferred, though it will be obvious there may be various modes of accomplishing
the same which may be adopted without departing from the spirit or main features
of the Invention.
The coils are constructed of metal pipes (whose ends are provided with screw
threads) the internal diamoter of which should be increased according to the size of
the boiler desired, the pipe is commenced to be wound from the centre outwards
in opposite directions, in the form of a double watch spring, one coil lying imme-
diately below the other, the ends being made to project a short distance from the
outside of the coil at opposite sides. These coils comprise the heating surface proper
of the boiler. The coils are connected to each other and to the reservoir, which is
placed above the coils, by means of two (or four as the case may be) hollow half round
columns in length nearly equal to the vertical height of the proposed boiler. They
may be bolted to the base of the furnace. Between these columns the coils are
placed one immediately above the other till the requisite number or height is
attained, their opposite ends being firmly bolted steam and water tight to the
columns, so that they may freely communicate with the hollow passages in the
columns. One of these columns (if only two are used) is connected to the bottom
of the reservoir or to one or more of its sections (if the latter is composed of
sections as proposed for the larger sizes), while the other or feed column is closed at
its upper end, but counected to the reservoir at its lower end by an auxiliary feed
pipe outside the casing or jacket of the boiler.
The operation is as follows:-The reservoir being filled with water to the proper
height and the fire being kindled in the furnace, the water in the coils is heated
and its specific gravity being consequently decreased it seeks the readiest escape into
the reservoir above, which is by the means of the unobstructed outlet in the exit
column. A partial vacuum being thus created in the coils, the water flows down
from the reservoir through the auxiliary feed pipe into the bottom of the feed column
which is connected with each of the series of coils. This column being closed at the
top the circulation is at once established through the coils, the rapidity of which is
dependent upon the intensity of combustion in the furnace, and such circulation of

page_text: the water through the coils readily absorbs and carries away all excess of heat which
would otherwise overheat the coils, drive out the water, and rapidly destroy the
heating surfaces.
"
It will be evident that there is hardly any practical limit under such conditions
to the pressure which may be safely generated and maintained in such coils of
pipe. By applying the same principle to the reservoir, vizt., constructing it in
sections of wrought or cast pipe of suitable diameter for the pressure of steam
required, equal safety is insured in the steam and water chambers.
These latter sections it is proposed to connect in radial ranks or rows by means of
pipes or their equivalents at the tops and bottoms, so that they practically forin one
continuous receptacle in which the water readily finds a common level, from whence
the steam is conveyed to the prime mover from the top of the reservoir in a pipe
which has a cominon connection with each of the sections.
As before remarked there are various obvious methods of effecting the different
objects, and the Inventor does not limit himself to the one here described,
although it is the cheapest, simplest, and most efficient of any which he has
devised.
The apparatus or "formner" upon which the spirals are made is constructed in
three separate portions. The first part is a cast-iron disk the diameter of which
is about the size of the completed spiral which it is desired to make. It has a
circular projection or boss in the centre, the diameter of which is that of the inner
diameter of the spiral of the contemplated coil. Around this boss or projection is
a groove large enough to receive the pipe to be coiled. The groove has a "pitch'
upward like the thread of a screw. This disk is bolted solidly flatwise upon a
firm foundation of convenient height. Upon the boss of this disk is placed another
disk of the same or a little larger diameter than the boss of the first disk, this also
has a groove which forms a continuation of the one just described upon the first
boss and with the same "pitch." This disk is, however, made in four sections so
that it shall readily fall to pieces and release the coil when completed. These two
disks are now surmounted by a third disk made substantially like the first, but
of considerably less diameter, the boss of which, however, is of the same diameter
as the lower one, but the groove is partially cut away at the bottom having no
"pitch." Albolt passes through the centre of each of these three disks. and they
are fastened firmly together and to the foundation by a screw nut. The lower
and larger disk is perforated with numerous holes for the insertion of pins to
retain the pipe when bent at any desired position on the periphery.
The proper length of pipe being placed at its middle in the groove on the boss
of the lower disk, and a pin being inserted in one of the perforations before
mentioned, by taking hold of one end of the pipe one or two men can readily coil
a pipe of three-fourth to one and a quarter inches in diameter around the boss.
of the lower disk. The operation is continued until the desired number of con-
volutions of of the lower half of the spiral has been obtained. The pin is then
inserted on the opposite side and the other half of the pipe is bent in the same
manner, following the grooves in the bosses already described, until it rises up
against the under surface of the upper disk where the remaining turns or con-
volutions may be readily completed resting closely upon the ones already finished.
Thus a double coil is quickly constructed of one length of pipe without a joint.
The natural spring of the pipe is sufficient to leave the required space between the
successive convolutions to allow free passage of the products of combustion, but if
more space should be required a strip of leather or similar material can be inserted
between the convolutions in the process of coiling which afterwards can be easily
removed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Bristow Hunt in the Great Seal Patent Office on the 2nd February 1877.
BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM BOILERS, AND IN
APPARATUS TO BE USED IN THE MANUFACTURE THEREOF." A. communication from
abroad by Alvan Dinsmore Brock, Engineer, of Washington, District of Columbia,
in the United States of America.
The objects of this Invention are—
To provide means for the production of steam at pressures very much exceeding
those in general use for locomotive or marine propulsion or for other useful pur-
poses, and with a degree of safety from dangerous explosions not attainable in
boilers of other constructions.
To construct and arrange water tube heating surfaces in such a manner that a
remarkable increase in the amount of such surfaces is exposed to the action of the
products of combustion as compared with other boilers, and at the same time to
reduce the weight and bulk in a proportional degree.
To dispose and arrange the heating surfaces in such a manner as to produce the
greatest possible effectiveness from the products of combustion.
To construct and arrange the coils of water tubes for steam generators so that
great economy of labor is attained.
To ensure a constant, effective, and natural circulation of water through the
tubes whereby danger of overheating is avoided, and the formation of scale or
sediment on the inside surfaces is in a great degree or wholly prevented.
To connect and combine a series of coils of water tubes so that each one of the
series shall have an independent connection with the general circulatory system, and
that ench coil can if desired be readily detached and replaced without disturbing
the others of the series.
To construct the steam and water reservoir of a water tube boiler in sections,
each of which shall be of comparatively small diameter, and yet be so combined
and connected each with the others that the water and steam may freely circulate
through all of them, allowing the water to stand at the same level in them all,
while at the same time contributing materially to the steam producing capacity, and
enabling the reservoir to resist almost unlimited pressures, the latter depending of
course upon the diameter and strength of the sections.
To provide such a combination of the water tube coils and the reservoir sections
as to attain extraordinary steam generating capacity combined with a correspond-
ing ability to withstand very high pressures, and so that in the event of a rupture
occurring in any one of the sections of the coils or of the reservoir the strain upon
those remaining shall be gradually and safely relieved.
To attain extreme portability by reduction of the size and weight of the sections
of water tubes and of the reservoir so that very large generators may be transported
in separate sections to positions and places inaccessible to boilers of the ordinary
type and equal capacity.
To attain a much greater temperature in the boiler furnace than is now practicable
through perfect circulation of the water in the sections.
To reduce the grate surface and increase the intensity of combustion as well
as the amount of heating surface, thereby largely increasing the effectiveness of the
latter.
To construct the sections of water tube boilers in interchangeable parts after the
so-called "assembling" system wherein each and every part is made to a certain
determined scale, and can be at once applied to any boiler of that size and type,
and whereby any required number of parts likely to be required under ordinary
circumstances can be kept in stock for emergencies.
To provide a steam generator which by the aid of special tools and machinery
may be produced in large numbers with extraordinary facility, and with a degree

page_text: of economy of materials and labor which shall place their first cost far below that
of boilers of the ordinary types.
To provide means for readily increasing the capacity of the generator (within
certain limits) by increasing its height which would only involve the substitution
of extra patterns for the castings of the circulating tubes, the lengthening of the
reservoir tubes, and the bolts for securing to them the tube heads, a correspondingly
lengthened jacket or casing for the complete generator, and an additional number
of coils. For example, a one half h. p. generator with three coils could be increased
to one h. p. by the addition of three coils and a corresponding increase in the
length of the reservoir tubes from seven inches to ten or twelve inches. The
two b. p. generator also could be thus increased to four h. p., the five h. p. to
ten, and the ten h. p. to twenty, and so on.
And to provide means for obviating one of the greatest difficulties heretoforo
encountered in constructing water tube coil generators, to wit, the destruction of
the joints by the contraction and expansion resulting from changes of temperature.
Both forms of coils, herein-after described and shewn on the annexed Drawings, are
in effect spiral springs, and all vibration or contraction and expansion is taken up
without undue strain upon the joints by which they are fastened to the circulating
columns.
The following construction is preferred as being the cheapest, simplest, and most
efficient, though it will be obvious that the same objects may be accomplished in
various equivalent ways.
The coils are constructed of metal pipes, the ends of which are screw-threaded,
and the internal diameter of which is proportioned to the size of the boiler desired.
The pipe is wound from the centre outwards in opposite directions in the form of a
double watch spring, one coil lying immediately below the other, the ends project-
ing a short distance at opposite sides of the coil. These coils, which comprise the
heating surface proper of the boiler, are connected to each other and to the reservoir
which is placed above them by means of hollow half-round columns, which may be
bolted to the base of the furnace, and are in length nearly equal to the height of
the boiler. The coils are placed between these columns above one another till the
requisite number or height is attained, their opposite ends being firmly bolted steam
and water tight to the columns so that they may freely communicate with the
hollow passages therein. One of the columns (if but two are used) is connected to
the bottom of the reservoir or to one or more of its sections (if the latter is com-
posed of sections as preferred for the larger sizes), while the other or feed column is
closed at its upper end, but connected to the reservoir at its lower end by an
auxiliary feed pipe outside the casing or jacket of the boiler.
The operation is as follows:-The reservoir being filled with water to the proper
height, and the fire being kindled in the furnace, the water in the coils is heated,
and its specific gravity being consequently decreased it secks the readiest escape
into the reservoir above, which is by means of the unobstructed outlet in the exit
column. A partial vacuum being thus created in the coils the water flows down
from the reservoir through the auxiliary feed pipe into the bottom of the feed
column, which as above mentioned is connected with each of the series of coils. As
this column is closed at the top, the circulation is at once established through the
coils, the rapidity thereof being dependent upon the intensity of combustion in the
furnace, and such circulation of the water through the coils readily absorbs and
carries away all excess of heat which would otherwise overheat the coils, drive out
the water, and rapidly destroy the heating surfaces.
It will be evident that there is hardly any practical limit under such conditions
to the pressure which may be safely generated and maintained in such coils of pipe.
By applying the same principle to the reservoir, viz., constructing it in sections of
wrought or cast pipe of suitable diameter for the pressure of steam required, equal
safety is ensured in the steam and water chambers. These latter sections it is
preferred to connect in radial ranks or rows by means of pipes or their equivalents
at the tops and bottoms, so that they practically form one continuous receptacle in

page_text: which the water readily finds a common level, and whence the steam is conveyed
to the prime mover from the top of the reservoir in a pipe having a common con-
nection with each of the sections.
As before remarked there are various obvious methods of effecting the different
objects, and the inventor does not limit himself to the one herein described,
although it is the cheapest, simplest, and most efficient of any which he has devised.
The apparatus or "former" upon which the spirals are made is constructed in
three separate portions. The first part is a cast iron disc, the diameter of which is
about the size of the completed spiral which it is desired to make. It has a circular
projection or boss in the centre, the diameter of which is that of the inner diameter
of the spiral of the contemplated coil. Around this boss or projection is a groove
large enough to receive the pipe to bo coiled. The groove has a pitch upward like
the thread of a screw. This disc is bolted solidly flatwise upon a firm foundation
of convenient height. Upon the boss of this disc is placed another disc of the same
or a little larger diameter than the boss of the first disc, this also has a groove
which forms a continuation of the one just described upon the first boss and with
the same pitch. This disc is, however, made in four sections so that it shall readily
fall to pieces and release the coil when completed. These two discs are now sur-
mounted by a third disc made substantially like the first, but of considerably less
diameter, the boss of which, however, is of the same diameter as the lower one, but
the groove is partially cut away at the bottom having no pitch. A bolt passes
through the centre of each of these three discs, and they are fastened firmly together
and to the foundation by a screw nut, the lower and larger disc is perforated with
numerous holes for the insertion of pins to retain the pipe when bent at any desired
position on the periphery.
The proper length of pipe being placed at its middle in the groove on the boss of
the lower disc, and a pin being inserted in one of the perforations before mentioned,
by taking hold of one end of the pipo one or two men can readily coil a pipe of
three-fourths to one and a quarter inches in diameter around the boss of the lower
disc. The operation is continued until the desired number of convolutions of the
lower half of the spiral has been attained. The pin is then inserted on the opposite
side and the other half of the pipe is bent in the same manner following the grooves
in the bosses already described, until it rises up against the under surface of the upper
disc, where the remaining turns or convolutions may be readily completed, resting
closely upon those already finished. Thus a double coil is quickly constructed of
one length of pipe without a joint.
The natural spring of the pipe is sufficient to leave the requisite space between
the successive convolutions to allow free passage of the products of combustion,
but if more space should be required a strip of leather or similar material can be
inserted between the convolutions in the process of coiling, which afterwards can
be easily removed.
Such being the nature and objects of the said Invention, I will now proceed to
describe more in detail the manner in which the same is to be or may be performed
or carried into practical effect, and in order that the same may be distinctly under-
stood, I have annexed hereunto one Sheet of Drawings illustrative thereof, and
have marked the same with figures and letters of reference corresponding with
those in the following explanation thereof, that is to say :-
One part of this Invention consists in an improved water tube steam generator,
of which Figures 1 to 10 on the annexed Drawings, illustrate the general arrange-
ment and details in the form in which the inventor prefers to construct it. Figures
11 and 12 show an alternative form of coil and fittings which may be employed
under cortain circumstances if desired.
Figure 1 is a central vertical section.
A represents the bed plate and B the circulating pipe connecting the reservoir
tubes with the inner circulating column or pipe. The columns or pipes B¹, B³ are
firmly socured upon the bed plate, so that B¹ is the inner inlet pipe to, and B³ the
inner exit pipe from the coils D. The pipe B³ is a continuation of B* and forms

page_text: the upper circulating pipe. It is bolted to a flange on the upper side of the tube
head F, which is inserted between the pipes B and B³. The circulating pipe B' is
secured to the tube head F in like manner as B is, and communicates therewith but
not directly, with the pipe B' as communication is prevented by the partition or
diaphragm b at the upper end of the circulating pipe B₁ for a purpose which will
presently be described. D represents the double spiral flat coils of pipe, only two
of which are shown for convenience, but any number of them may be used according
to the capacity of generator desired. These coils are secured to the circulating
tubes B¹ and B by fittings or elbows and bolts d, their opposite ends having free
communication with the circulating columns B¹ and B*. A series of vertical tubes E
is secured between the tube heads F and F by means of bolts e. Each of these
tube heads consists of a series of sockets for the reception of the vertical tubes, the
sockets being united by connecting pipes f for the purpose of establishing a free
circulation of the water, and the proper communication of the steam within the
tubes. An increase of steam space is provided above the centre tube by an elongated
cap attached to the top tube head 1ª so that superheated and dried steam may be
obtained through the steam outlet f. The pipe B communicates at one end with
the lower tube head F through the opening b, while the lower end of the said pipe
is attached to and communicates with the inlet column B' by means of the lower
nozzle b. A water feed pipe C is inserted in the top of the pipe B, and is preferably
extended some distance downward within the same. The generator is enclosed
within a casing G provided with proper fire and ash doors, and extending from the
bed plate to the top of the vertical tubes, above which is placed a hood or uptake H
to which the chimney is connected. The casing G may be lined with a non-
conducting material to prevent the escape of heat, or be provided with an internal
jacket enclosing a dead air space, or both these expedients may be employed, and it
is preferably divided vertically into two sections hinged or bolted together, so that
one or both may be readily removed to admit of access to the several parts. There
is also provided a door in the casing so placed as to give access to the coils for
renewal, repair, or cleaning. The grate I is placed at a suitable distance below
the lowest coil D.
Figure 2 is a sectional plan view of the coil and its method of connection to the
circulating tubes. B' represents the inner inlet circulating column, and B³ the inner
exit circulating column, d the quarter-turn or elbow connecting the coils to the
circulating columns, and d¹ the bolts by which the coils are secured firmly in their
places steam and water tight.
Figure 3 is a side view in elevation of the steam and water reservoir.
Figure 4 is a sectional plan view of the lower tube head F which with slight
modifications serves also for the upper tube head F".
Be and B7 represent short flanged pipos for the reception and continuation of the
circulating columns. Bs the sockets for the reception of the vertical tubes E, and e
the bolts which secure the tube heads and vertical tubes together.
.
Figure 5 is a horizontal section of one form of a fitting connecting a coil D to one
of the circulating columns B'.
•
represents the quarter turn or elbow, and d¹ the bolt by which the coil is united
to the circulating column, the bolt being in this instance tapped into the inner end
of the quarter turn and having a head on its outer end.
Figure 6 is a modification of Figure 5 showing the coil united to the circulating
column by a union coupling.
Figure 7 is another modification of Figure 5 shewing the coil united to the
column by a flange and two bolts.
Figure 8 is a view partly in section of another form of coil, illustrating also the
method devised for the connection of a series of them to the circulating columns.
This Figure shows a net of coils, the inner one K being of comparatively small
internal diameter for convenience of bending within a small circle, its length and
amount of heating surface being proportioned to the quantity of water which it
will deliver to the reservoir above without entire conversion into steam. The next

page_text: contiguous coil K' is placed around it, its inner diameter being about one-half inch
larger than tho external diameter of the preceding coil, so as to afford space for the
ascent between them of the products of combustion. The third coil K" is necessarily
longer than the first or second of the series, and has a larger internal diameter or
orifice. The series may thus be carried on in proper proportions to any size or
capacity desired. Each coil may be connected to a common horizontal pipe across
the centre of the series at top and bottom, by means of the devices shown in
Figures 5, 6, and 7, and these horizontal pipes in their turn are connected to the
circulating columns by means of the ordinary screw joint if desired, though it is
preferred to make the joint as shewn in Figures 2 and 5. This arrangement
of coils possesses some obvious advantages over that shewn in Figure 1, and is
moreover simple, compact, and effective to a remarkable degree.
Figure 9 is a plan or top view of the arrangement shown in Figure 8.
Figure 10 is a diagram of a nest or battery of the improved generators for marine
or other purposes where greater steaming capacity is desired than would be con-
venient in one generator. By combining them in this or some equivalent form, it
is obvious that they may be adapted to any purpose for which large quantities of
steam are required, and to almost any situation.
Figure 11 is a plan view of a single spiral flat coil.
And Figure 12 a vertical section shewing the ends of a series of coils, each
screwed into a separate socket MI, the several sockets being turned or finished on
their ends and united together by a central bolt N and nut N¹.
The operation of the improved generator is as follows:-The generator being
filled to the water line, and the fire being kindled, the water in the coils D is heated,
its specific gravity being thereby reduced, it rises, flows out of the coils at i, into:
the circulating column B, and up into the reservoir tubes E, following the course
of the large arrows. A tendency to form a vacuum being thus created, the colder
water flows in from the tube B, through B', to the coils D, and as the temperature
is gradually increased, steam also forms in the coils, which very materially accelerates
the circulation thus established. The feed water necessary to supply the loss of 3
water which escapes as steam is taken in at C, and assists the circulation both by
its momentum and superior gravity. This circulation would be maintained under
ordinary circumstances if there were free communication between the circulating
columns B and B', because, as will be observed, the inlet orifices of the coils D,
are below the outlet orifices i, but as it is desirable in most cases to produce an 3
intense fire by a strong draught there would then be considerable danger of the
water being forced out of the coils D at both inlet and outlet orifices, it escaping
into the reservoir tubes by the columns B¹ and B', as well as by the columns B
and B³, in which case the circulation would be destroyed, the coils would become
overheated, and speedily burnt out. But by the stoppage of communication between
B¹ and B', by means of the diaphragm b1, the water is forced in the direction of B
and B, and the excess of heat is thus imparted to the water as it passes through
the coils.
The Inventor has found that with coils of proper length and internal diameter a
blast of steam of 300 lbs. per square inch, the jet orifice of which is one half inch 4
internal diameter, may be used to urge the fire without the slightest danger to the
integrity of the coils. With coils one and one fourth inches internal diameter and
thirty feet in length, the inventor has twice succeeded in melting down seven
square feet of grate surface, while the coils in immediate contact with the intense
flame have not been injured in the slightest degree.
Another part of this Invention consistsin a double spiral coil of pipe adapted for use
in the generator herein-before described for generating steam in other structures,
or for condensing it, for heating feed water for boilers, and for heat radiating
purposes.
5
The advantages of this double or right and left coil are economy of space and the 5
provision of a large amount of heating, condensing, generating, or radiating
surforee

page_text: Referring to Figures 1 and 2 it will be seen that the pipe is coiled spirally in
two directions, at top from right to left, and at bottom from left to right, or vice
versd, and that its ends are in different horizontal planes, which last stated fact, as
herein-before shewn, is of special advantage in a generator constructed as before
described. It might also be coiled conically inward and outward towards and from
a central point with lead in one direction, and thus likewise provide a double coil.
A third part of this Invention consists in an apparatus for bending metal pipes
which is represented in Figures 13 to 16 inclusive.
Coiled pipes are used for various purposes, and they have been constructed in flat
and cylindrical forms; but heretofore great difficulty and expense have been
encountered in producing double spiral coils for the want of a device with which to
bend them into true and perfect forms, nor has it heretofore been attempted to
produce a right and left or double spiral coil.
By the use of the device herein described metal pipes can be bent with compara-
tively little expense, and in the forms best adapted for many purposes known in
the utilization of steam.
Figure 13 is a plan view of the coiling hub with the coil in place; Figure 14 a
side elevation of the same.
Figure 15 a plan view of the coiling hub, the coil being removed, shewing the
sectional blocks of the hub.
And Figure 16 a section on line x, x, shewing the grooves of the hub with the
coil inserted.
I represents the base plate of the hub, in which are the holes 2 for inserting
pins to hold the pipe in place; 3 represents removable sections of the hub; 4, the
coil in place on the hub; 5, the grooves of the hub; "G, a bolt passing through the
hub sections; and 7, bolts for securing the base plate of the hub to any solid
foundation.
•
The operation of this apparatus is as follows:-The hub sections are first firmly
secured together by the bolt 6. The pipe is then placed across the base plate near
the middle of its length, and inserted in the lower groove, nearly around which it is
once turned or carried; it then rises through a channel between the grooves into
the upper groove of the hub, around which it is taken one full turn. The end of
the upper coil is then secured by inserting a pin in one of the holes 2 in the base
plate. The lower coil is then turned to a completion, and when completed and
resting on the base plate serves as a base to complete the upper coil.
In order to remove the pipe when thus formed into a right and left flat coil the
bolt which holds the hub in place is removed, and on displacing the middle section
of the hub, which is in four pieces, the coil may be readily taken off.
Having now described the nature and objects of the said Invention for "Im-
provements in the Construction of Steam Boilers, and in Apparatus to be used in
the Manufacture thereof," together with the manner in which the same is to be or
may be performed or carried into practical effect, I would remark in conclusion
that I claim as the Invention communicated to me by the said Alvan Dinsmore
Brock-
First. The combination in a steain generator of a steam and water chamber with
a coil or system of coils of pipes situated at a level below the chamber and imme-
diately above the grate or fire surface, said combination being effected by means of
two or more circulating tubes connecting with the chamber at or below the water
line therein, and thence directly with the coil or system of coils, and in such manner
that the water is conducted from the chamber directly to the coils through one or
more of such tubes while the steam and water is conducted from the coils directly
back to the chamber through the other tube or tubes in such manner also that the
tube or tubes conducting the water to the coils shall be connected with the same at
a point lower than the tube or tubes which conduct the steam and water to the
chamber, thus effecting a rapid and continuous circulation throughout the combi-
nation.
Second. The combination in a steam generator of two or more vertical circulating

page_text: Lubes, a system of coils of pipe, each connected at its ends to the said tubes by
means of a quarter turn union or otherwise, a transverse diaphragm placed in one of
the tubes above the level of the coils, a steam and water chamber communicating
with the tubes above the level of the diaphragm, and a pipe which communicates at
its top with the chamber, and at its bottom with one of the said tubes, at a point
below the diaphragm therein.
.
Third. The combination in a steam generator of a steam and water chamber with
a coil or system of coils united to two or more circulating tubes as aforesaid, and in
such manner that the water is not conducted from the chamber to the coil or coils
directly through the said tubes, but by means of one or more conduct pipes con-
nected at the upper ends with the chamber below the water line, and at the lower
ends with one or more of the said tubes at a point below the entire system of coils.
Fourth. In a steam generator, the construction of a steam and water chamber
composed of a series of vertical tubes, each united at the ends to tube heads or
sockets fitted to receive them by means of bolts passing longitudinally through the
tubes and sockets, and each communicating with the mass through a system of
pipes in such manner as to form a common reservoir.
Fifth. A metal pipe bent spirally so as to form a double coil.
And, Sixth. An apparatus for coiling metal pipes, consisting of a base plate, a
grooved hub formed in removable sections, and a connecting pin or bolt.
The whole being substantially as herein-above described and as illustrated on the
accompanying Sheet of Drawings.
In witness whereof, I, the said Bristow Hunt, have hereunto set my hand
and seal, this Thirty-first day of January, in the year of our Lord One
thousand eight hundred and seventy-seven.
BRISTOW HUNT. (L.S.)