US634299A - Steam-boiler. - Google Patents

Description

No. 634,299. Patented Oct. 3, I899. D. P. JONES.

STEAM BOILER.

(Application filed Apr. 4, 1898.)

(No Model.) 2 Sheets-Sheet l.

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Patented Oct. 3,1899;

D. P. JONES. STEAM BOILER. (Application filed A r. 4, 1898.)

2 Sheets-Sheet 2 (No Model.)

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.referencesign whereverit occurs throughout UNITE'D' STATES PATENT rinse.

DAVID P. JONES, or CHICAGO, ILLINOIS.

STEAM-BOILER.

SPEGIFIG ATION forming part of Letters Patent No. 634,299, dated October 3, 1899.

Application filed April 4, 1898. Serial No. 676,484. (No model.)

To aZZ whom it may concern.-

Be it known that 1, DAVID P. JONES, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Steam-Boiler, of which the following is a specification.

This invention relates to steam-boilers, and particularly to water-tube boilers. I

The object of the invention is to improve the construction and arrangement of steamboilers and to render the same more efficient in operation.

The invention consists, substantially, in the construction, combination, location, and relative arrangement of parts, all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally specifically pointed out in the appended claims.

Referring to the accompanying drawings and to the various views and reference-signs appearing thereon, Figure 1 is a transverse sectional View of a boiler embodying the principles of my invention,the section being taken on the line Z l/V, Fig; 2, and the casing being omitted. 'Fig- 2 is a longitudinal sectional view of thesame, the section being taken on the line X X X X Y,Fig. 1. Fig. 3 is a front elevation of the boiler. Fig. 4: is a side elevation of the same without the side casing, the end and-top casing 75 t 25 being shown in vertical section. Fig. 5 is an enlarged broken detail view showing the manner of expanding the ends of the water-tubes into the tubesheets. Fig. 6 is an enlarged detail broken view showing the arrangement of nipples delivering from the feed-pipes into the down-v comer-tubes. Fig. 7 is an enlarged broken detail view showing the construction and arrangement of bathe-tiling. Fig. 8 is a dc tached detail View showing the arrangement for mounting and supporting the water-baffle in place. Fig. 9 is a detail View showing method of fianging the open sides of the segmental drums in order to secure the tubesheets thereto.

The same part is designated by the'sanie the several views.

Heretofore in the construction Ofsteamboilers, and particularly boilers of the type employing water-tubes, it has been difficult is greatly increased.

to arrange the'water-tubes so as to present the most effective heating surface to the gases and other products of combustion in the furnace-chamber without incurring the serious objection of unduly straining the joints where the ends of the tubes are expanded or otherwise secu red into the tube-sheets. Moreover, in prior constructions of steam-boilers of the class to which the present invention relates it has not been practicable to easily and readily handle the parts of the boiler for transportation to and erection at the destination thereof. Again, it has been difficult to secure a proper and eflicient circulation through the water-tubes without the upward and downward currents interfering with each other.

It is the purpose of the present invention to avoid the objections and difficulties above noted and to provide a construction and arrangement of water-tube boiler wherein the water-tubes are so arranged that expansion.

is efficiently provided for without injurious strains resulting upon the joints where the ends of the tubes are expanded or otherwise secured in the tube-sheets, wherein the handling, shipment, and assemblage of the parts are greatly facilitated, wherein the boilertubes present an efficient heatin -surface to the gases or other products of combustion from the furnace-chamber, wherein access to the various parts for inspection and repair is facilitated, wherein efficient circulation through the tubes is maintained, wherein a large area of furnace-chamber is provided,

wherein the gases are perfectly consumed,

wherein the height of the boiler may be suitably regulated to correspond to the exigencies of space into which the boiler is to be received, wherein the cleaning of the boilertubes is not interfered with, and wherein the efficiency of the boiler in steam production In carrying out my invention I provide one or more sets of chambers B B O C. These chambers may be of any suitable form of construction, but preferably, and as shown, I employ for these chambers suitable drums in the form of segmental cylinders. The invention, however, is not intended to be limited or confined to this particular construction. On the open sides of the segmental drums B O are suitably mounted tube-sheets F, and

lOO

' to different angles.

said tube-sheets are arranged to receive the ends of the water-tubes a (I. In order to elliciently support tube-sheets F on the lower segmental drums C, the edges of said segmental drums are bent back or doubled upon themselves, as shown at H, Fig. 9, thus stiffening the flanges to which the tube-sheets are secured. The drums B O are arranged in pairs, and a set of water-tubes a are arranged to connect the members of each pairof drums B C, said tubes being connected at one end to the tube-sheet F of one drum and at the other end to the tube-sheet F of the other drum. The plane cutting the drum B to form said drum into a segment, and hence the plane of tube-sheet F, mounted or secured upon such drum, is arranged angularly with respect to the plane cutting the corresponding drum 0, and hence also theplane of tubesheet F, mounted or otherwise secured to said drum 0. In the particular form shown, to which, however, the invention isnot limited, these planes intersect each other at right a11- gles. The connecting series of water-tubes a a are bent at a suitable pointintermediate the ends thereof, so as to present their respective ends normal to the segmental planes above referred to, the ends of said tubes a a being straight from the bent portion thereof, the angle between the straight end portions of each tube a a being the same as the angle between the segmental planes above mentioned. The cooperating pair of drums 13 C are preferably arranged to one side of the furnace-chamber, as clearly shown, the bends in the series of connecting-tubes (I being presented inwardly into the furnace-chamber. It is evident that tube-sheets F may be either straight or plane plates suitably constructed to receive the ends of the tubes a a, or may be curved, if desired, and as shown.

As shown, and preferably, all the tubes a a are bent to the same angle. Therefore I avoid the necessity of carrying in stock extra or auxiliary tubes for repairs which are bent In other words, the repair or extra tubes may all be uniform and can be readily adapted to replace any one of the tubes in the boiler by merely cutting off the ends thereof to the required length. By this construction, wherein a single bend is provided in each tube and wherein the portions of the tube from the bend to the ends thereof are straight and substantially at right angles to each other, it will be seen that the cleaning of the tubes is not interfered with.

In Fig. 5 I have shown a simple arrangement for expanding or otherwise connecting the ends of the tubes a a into the tube-sheet F. In order to facilitate the ready assemblage of the tubes a with the respective ends thereof in suitable relation to be expanded into the perforations or openings in the tubesheets and also to facilitate the removal or insertion of individual tubes a for repair or replacement, the holes or openings in the tube-sheets F, which receive the ends of the tubes (1, are made slightly larger than the external diameter of the end of the tube, as clearly shown. By this arrangement it will be readily seen that the tube can be slightly rocked or swung laterally after one end thereof has been inserted through a tube-sheet in order that the otherend may be easily brought into register with the proper hole or opening in the other tube-sheet. This is a practical feature of importance, as thereby the easy assemblage of the tubes a is effected. When the ends of the tubes a are finally inserted in the proper holes or perforations in the tubesheets, suitable thimbles or sleeves a are slipped thereon, and these thimbles are expanded with the ends of the tubes to elfect the desired securing of the tubes in the tubesheets, thus forming an efficient joint.

In the construction of boilers it is a matter of great importance to secure as large an area as possible of the furnace-chamber in order that the combustion of fuel and of the gases may be complete. It is also of great importance to provide against the possible escape of unconsu med gases, as such escape denotes not only incompleteness of combustion, but also less of efiiciency in the boiler. In the present case it is obvious that if gases given off from the fuel are permitted to come in contact with the lower ends of tubes to at or near their joint with the lower drums O, and hence at a point where such tubes are coldest, the temperature of such gases would be reduced to a point such as to prevent their ready combustion, and hence such gases will escape or be carried off by the draft and onto the uptake or chimney in an uneonsumed condition. My invention contemplates the provision of means whereby these objections are avoided, and the desired result is secured by providing side walls 7t 01 on the respective sides of the grate-surface o of the furnace-chamber. These side walls are made to extend as high as the position of tubes at a will permit, and they serve to confinethe gases given off from the fuel to the furnace-chamber until such gases are raised to a temperature at which combustion takes place before they come in contact with the tubes, thus insuring completeness of combustion of the fuel.

In the particular form shown, to which, however, the invention is not limited or restricted, two sets of drums B C ll O are employed, one set being arranged on each side of the furnace-chamber.

Reference-sign m designates adivision-wall between that part of the furnacechamber which supplies heat to one set of tubes and the part of such chamber which supplies heat to the other set of tubes, and the bends in the set of tubes a on one side of the chamber are presented toward the bends in the set of tubes on the other side of the chamber, and also toward the center of the chamber, as clearly shown. The purpose of this divisionwall is to aid in the ready ignition of fresh fuel when supplied to the grate.

This object is accomplished by extending the divisionwall to a suitable height in the furnace-chamber-say to a point above the fire. This wall is constructed of fire-brick or other suitable refractory material and becomes heated to a high temperature and enables fresh fuel to become ignited readily.

Reference-sign E designates the fire-arch, constructed of fire-brick or other suitable material and suitably supported, as shown in Fig. 1, upon the inner row or rows of water tubes (1. Of course it is evident that where only one set of drums B O is employed and only one series of tubes a are provided the division-wall m may be extended all the Way up to the fire-arch. The tube-sheet F and the flanged joint H of the lower drums O are suitably protected from the direct heat of the furnace-chamber by a suitable inclosing casing of fire-brick, as clearly shown.

In order to suitably deflect the heated airgases or other products of combustion from the furnace-chamber, so as to properly impinge against the heatingsurface presented by the tubes at, I provide suitable baffle plates or tiling d d c c. It will be seen that the baffle-plates c are arranged, respectively, on the outer and inside of each series of tubes or. (See Fig. 1.) The lower and outer baffle-plate or lining a does not extend the extreme length of the boiler, but terminates at the line r r, Fig. 2, thus leaving an open space between the point r r and the point 8 8. Similarly the upper and inner bafiie-plate 0 extends only partially the length of the boiler from the opposite end thereof, terminating at the line r 1, thus leaving the space between r r and s 3 open, thus providing a passage, as indicated by the arrows in Fig. 2, for the heated air and gases from the furnace to freely circulate between the tubes at back and forth throughout the length of the boiler until they finally reach the uptake orchimney, it being observed that such heated air or gases always impinge upon the heating-surface of the tubes on lines normal to the axes of such tubes. The baffle-plate d may be a single perforated plate, the tubes a passing through the perforations therein; but,if desired,and as shown in Fig. 7, and preferably, this baflie-tilingcomprises a series of strips provided with openings or seats on the edges thereof which register with corresponding openings or seats on the proximate edge of the next adjacent strip to form passages for the tubes a. These baffle-strips are arranged approximately horizontally, as shown in Fig. 1, and are suitably supported, as by means of the blocks J J, and serve to cause the products of combustion from the furnace chamber' to traverse the proper course to suitably encounter the heating-surface ofthe tubes.

From the foregoing description it will be readily seen that I provide an arrangement wherein expansion and contraction of the tubes at a will not seriously injure or affect the joints of such tubes in the tube-sheets,

tubes.

such expansion being taken up in-the bends in such tubes. It will also be readily seen that the products of combustion are caused to circulate freely between the tubes and always on lines normal to the axes of the tubes, thus providing an exceedingly efficient arrangement for steam production.

I will now describe the arrangement for maintaining circulation, particular reference being had to Figs. 1, 3, and 6, wherein reference-sign Z designates feed-pipes arranged to deliver into or through drum B. These feedpipes may be controlled by suitable checkvalves L. (See Fig. 3.) Reference-sign b designates suitable pipes arranged to open communication between each pair of drums B C. These pipes I designate downcomer- They are preferably arranged outside of the series of water-tubes a and are substantially straight and vertical, and hence are shorter in length than the tubes a. These downcomer-tubes bare also of larger diameter than the water-tubes. By reason of the location of these downeomer-tubes outside -of the tubes a, and hence at a point where they are subjected to less heat than the water-tubes a, and by reason of their larger size -it will be readily seen that I provide an ex ceedingly efficient arrangement for securing and maintaining upward circulation through the pipes a. From supply-pipe Z extend nipplesp into the open ends of downcomer-tubes b, as clearly shown in Figs. 1 and 6, whereby feed-water may be readily supplied to the water-drum O.

In order that the feed-water may be heated before being admitted to water-drum C, the feed-water may be supplied to feed-pipe Z through a series of coils h, suitably arranged in the furnace-chamber above fire-wall E, as clearly shown in Figs. 1 and 2. In this manner I utilize the heat from the hot air or gases from the furnace-chamber after such air and gases have passed from the tubes at and while on their way to the uptake or chimney. ably supported and arranged within the casing 25, which incloses the boiler, is the steam drum or chamber D. This chamber may be of any suitable construction and arrangement. In the form shown in full lines in Figs. 1 and 3 a single cylinder is employed for the steamdrum. It is obvious, however, that two or more cylinders, drums, or chambers may be employed, as indicated in dotted lines at e, Figs. 1 and 3. The invention therefore is not limited or confined in this respect. The use of two or more such steam drums or cylinders is advantageous, one for each set of drums B O and tubes Ct, where it may be desired to use only one side or set of tubes a and drums B 0. Suitable pipes g deliver from drums B into steam-drum D.

By arranging the steam-drum D within the casing and in the space between the upper drums B and above the fire-arch E the steam in such drum D may be maintained superheated by the heat from the gases passing Suit ICC

from the water-tubes a to the uptake or chimney. Steam-drum I) may be provided with a drain-pipe V, through which any condensation may be withdrawn from such drum. Reference-sign E, Fig. 3, designates the steampipe delivering from steam-drum D.

In order to prevent any water which may be contained in drum B from being forced into the steam-pipes g, which deliver from such drum B into steamdrum D, I provide a baffle-plate f, which, if desired, may be perforated within drum B, so arranged as to protect the mouth of pipes g This baflie-plate is suitably secured at one edge thereof upon the inside surface of drum B and at the other edge thereof is supported or held by a series of brackets f, thereby suitably offsetting said battle-plate and permitting the steam contained in said dru m B to pass into and through pipes but preventing any water contained in said drum B from passing into pipes 9. (See Figs. 1 and 8.)

Of course it will be obvious that the relative sizes of the parts is no part of the invention, and I therefore do not limit or confine myself to sizes or proportions of the parts. It is also evident that only one or more downcomer-tubes b may be employed to stimulate the circulation through drums B O and tubes at.

In order to impart strength and rigidity to the structure, if desired the inner rows of tubes a which support fire-arch E, maybe made heavier or thicker than the other tubes, thus efliciently supporting such fire-arch.

By arranging the feed-pipes Z to extend throughout the length of drums B and having the nipples p delivering into the upper ends of downcomer-tubes b it will be seen that the feed-water is delivered into the downcoinertubes in the same direction as the direction of flow'of the current of circulation through the tubes and drums B 0, thus avoiding any retardation of the circulation, but, on the contrary, stimulating such circulation.

From the construction above described it will be readily seen that the height of the boiler may be regulated without disturbing the standard construction and relative arrangement of drums B O and tubes at by merely locating the upper drums B farther apart or nearer together-as, for instance, by rocking each set about the longitudinal axis T of drum 0, as indicated by the radii T U in Fig. 1. This is an important feature for the reason thatitsometimes becomesimportant to economize the space into which the boiler is to be received, and hence in my construction as above described after the parts of the boiler have arrived at their destination the height of the boiler may be regulated to correspond with the space into which the boiler is to be received and without material alteration in the construction and without disturbing the relative arrangement of the series of tubes at of each set.

Reference-sign Q, Fig. 3, designates fluedoors through which access to the interior of the boiler-casing may be had, and referencesign M designates the furnace-doors. Reference-sign 1 Fig.3, designates angle-iron supports.

\Vhen erected, a boiler constructed in accordance with the principles of myinvention may be held in place by any suitable or convenient arrangement of girders or supports, and the lower drums C may be suspended by angle-irons, ties, or otherwise from the upper drum or in any other suitable manner, dependent upon the conditions of use of the boiler, whether on land or at sea as a marine boiler, WVhen used as a marine boiler, the outside covering or casing t 25 may be of asbestos suitably secured to sheet-iron or otherwise supported and properly stiffened,while in the case of land boilers the casing maybe of brick or masonry work.

From the foregoing description it will be seen that a boiler constructed in accordance with the principles of my invention may be shipped to the point of destination in sections, thus economizing space in transportation, the several sections or parts being assembled at the point of destination. This is an importaut feature where the boiler is designed for use in mines or as a marine boiler on board ship. In the latter case the parts can be readily passed through the fire or engine room hatches.

Experience has demonstrated that a more efficient steam production is secured in water-tube boilers Where the portions of the tubes with which the current of heated air and gases contacts are inclined relative to the horizontal. In the construction and arrangement shown in the accompanying drawings and above described I embody an arrangement wherein this advantage is availed of. It will be seen that the straight portions of the tubes at, which extend from the bends therein to drums C, are inclined to the horizontal. It will also be seen that the other or upper straight portions of these tubes, extending from the bends to drums B, are inclined more acutely than the lower straight portions. Therefore a greater efliciency in steam generation would be secured in the upper portions of the tubes than in the lower portions, provided both portions are subjected to the same degree of heat. It is evident, however, that a portion of the heat of the air, gases, and other products of combustion is extracted and used up in heating the lower portions of the tubes while such air and gases are circulating between the lower portions of the tubes in the space within lower baffle-plate c c and beneath horizontal bathe-plate (Z cl, and therefore by the time'such air and gases reach the upper portions of the tubes their temperature is diminished. Under ordinary conditions this reduced temperature of the air and gases would naturally result in a loss of chiciency in steam production in the upper portions of the tubes. In my construction by arranging the upper portions of the tubes (.4

more acutely to the horizontal than the lower portions I compensate in a large measure for the difference in temperature of the air or gases above noted withreference to the steamproducing power of the two portions of the tubes. This I regard as an important feature, inasmuch as it results in an increased efficiency of the boiler as a whole.

'WhileI have shown and described a specific construction of boiler, I desire it to be understood that many changes in and variations from the specific construction shown and described would readily suggest themselves to persons skilled in the art and still fall within the spirit and scope of my invention. I do not desire, therefore, to be limited or restricted to the exact construction and arrangement shown and described; but,

Having now set forth the object and nature of my invention and a form of apparatus embodying the principles thereof, what I claim as new and useful, and desire to secure by Letters Patent, is

1. In a boiler, a furnace-chamber, an upper and a lower drum extending longitudinally of said chamber, water-tubes connecting such drums, said tubes being bent or deflected intermediate their ends into the furnace-chamber, a horizontally-arranged baflie-plate made in sections or strips and having registering seats in the meeting edges thereof through which said tubes pass, said baffle-plate being arranged at about the bends in said tubes, and a lower outer and an upper inner baffleplate, said baffle-plates cooperating to conduct the products of combustion in a path normal to the axes of the lower ends of such tubes and .returning the same in a similar path with respect to the upper ends of said tubes, as and for the purpose set forth.

2. In a boiler, a f urnace-chamber, an upper and a lower drum arranged to one side and extending longitudinally thereof, tubes connected at the respective ends thereof to such drums, said tubes being bent or deflected intermediate their ends intosaid chamber, a series of downcomer-tubes arranged outside of said tubes and respectively connecting said drums, a feed-pipe delivering into the upper of said drums, and nipples delivering from said feed-pipe into said downcomer-tubes, as and for the purpose set forth.

3. In a boiler, a furnace-chamber, an upper and a lower drum arranged to one side and extending longitudinally thereof, tubes connected at the respective ends thereof to said drums, said tubes being bent or deflected intermediate their ends into said chamber, a fire-arch supported by the inner row of tubes, a feed-water coil arranged in said chamber above such fire-arch, a feed-pipe arranged to deliver into the upper of said drums and communicating with such coil, downcomer-tubes respectively connecting said drums, and nipples delivering from said feed-pipe into said downcomer-tubes, as and for the purpose set forth.

a. In a boiler, a furnace-chamber, an upper and a lower drum arranged to one side and extending longitudinally thereof, tube-sheets mounted on said drums, said tube-sheets respectively arranged in planes intersecting each other at right angles and having perforations, a series of water-tubes having their ends arranged to be received in the perforations in said sheets, and thimbles arranged in said perforations and adapted to receive the ends of said tubes, whereby by expanding the ends of said tubes and thimbles an efflcient joint is formed between said tubes and sheets, said tubes being bent or deflected at a single point intermediate the ends thereof into the furnace-chamber, as and for the purpose set forth.

5. In a steam-boiler, a f u mace-chamber, an

upper and a lower drum arranged to one side thereof, water-tubes connecting such drums and bent or deflected intermediate their ends into said chamber, a steam-dru m, pipes connecting said steam-drum and the upper of said first-mentioned drums, and a water-baffle arranged Within said upper drum to protect the mouth of said pipes from the admission of Water from said upper drum, as and for the purpose set forth.

' 6. In a steam-boiler, a f u rnace'chamber, an upper and a lower drum arranged on one side of said chamber, said drums being formed of segments of cylinders, the cutting plane of the segment of one cylinder intersecting the cutting plane of the segment of the other cylinder at substantially right angles, tube-sheets mounted on the segmental surface of said cyl inders and water-tubes connected to said tubesheetsat the respective ends thereof, said ends being normal to the plane of their respective tube-sheets, said tubes being bent intermediate the ends thereof at angles corresponding to the angle between the cuttingplane of the segments of said cylinders, as and for the purpose set forth.

7. In a boiler, afurnace-chamber, an upper and a lower drum mounted at each side of such chamber, tubes connecting each pair of said drums, said tubes being bent angularly intermediate their ends so as to project into such chamber, and side walls for said chamber, said side walls arranged inside of the lower ends of said tubes and extending upwardly to said tubes, as and for the purpose set forth.

8. In aboiler, a furnace-chamber, an upper and a lower drum mounted on each side of said chamber and extending longitudinally thereof, tubes connecting each pair of said drums, said tubes being angularly bent intermediate their ends so as to projectinto said chamber, and a division-wall for said chamber, said division-wall arranged longitudinally of said chamber about midway thereof and extending above the fire, whereby the ignition of fresh fuel is aided, as and for the purpose set forth.

9. In a boiler, a furnace-chamber, an upper and a lower segmental drum mounted on opposite sides thereof, the edges of said segmental'drums being flanged, said flanges being reinforced by being bent or doubled back upon themselves, tnbesheets mounted on said reinforced flanges, and tubes respectively connected at the ends thereof to each pair of tube-sheets, as and for the purpose set forth.

10. In a boiler, a pairof drums, in combination with water-tubes connecting such drums, each of said tubes having a single bend therein intermediate its ends, the bent portions of such tubes arranged to project int-o the fur mace-chamber transversely thereof, as and for the purpose set forth.

ll. Ina boiler, afurnace-chamber, a pair of drums arranged to extend longitudinally of said chamber atone side of the top and bottom thereof, tube-sheets respectively supported by said drums, said sheets arranged in planes intersecting each other at right angles, and tubes each having a single bond therein intermediate its ends, the bends projecting transversely into the furnace-chamber, the ends of said tubes connected to said tubesheets, as and for the purpose set forth.

12. In a boiler, a furnace-chamber, a pair of drums arranged to extend longitudinally of said chamber at one side of the top and bottom thereof, and tubes, each having a single bend therein, intermediate its ends, the ends of such tube from. such bend extending in straight lines substantially at right angles to each other, and respectively connected to said drums, as and for the purpose set forth.

13. In aboilcr, afurnace-chamber, a pair of drums arranged at each side of said chamber to extend longitudinally thereof, one member of each pair being arranged at the top and the other at the bottom of the furnace, a set of tubes arranged to connect each pair of dru ins, each tube of each set being bent at a single point intermediate its ends, the end portions of such tubes extending in straight lines from said bend and at substantially right angles to each other, the bends of said sets of tubes extending into the furnace-chamber, as and for the purpose set forth.

14:. In a boiler, afurnaec-chamber, a pair of drums arranged at the top and bottom of said chamber and extending longitudinally thereof, water-tubes connected at the ends to said drums and bent intermediate their ends-into the furnace-cha1nber, transversely thereof, and a lire-arch arranged to be supported upon the extreme inner tubes, as and for the purpose set forth.

15. In a boiler, a furnace-chamber, drums arranged to one side of said chamber at the top and bottom thereof and extending longitudinally thereof, water-tubes bent intermediate their ends and connected at their ends to said drums respectively, the bends of said tubes projecting into said chamber, in combination with substantially straight downcomer-tubes arranged outside of said firstmentioned tubes and connected respectively to said drums, and a steam-drum, arranged above said chamber, and pipes connecting said steam-drum with the upper of said firstmentioned drums, as and for the purpose set forth.

16. In aboilcr, afurnace-chamber, an upper and a lower drum arranged on one side of said chamber and extending longitudinally thereof, tubes connected at the respective ends thereof to said drums, said tubes bent intermediate their ends transversely into said chamber, a steam-drum arranged above said chamber and parallel with said first-mentioned drum,and pipes connecting said drums, as and for the purpose set forth.

17. In a boiler, a furnaee-chamber, drums arranged at the top and bottom of said chamher, and extending longitudinally thereof, tubes connected at the respective ends thereof to said drums and bent intermediate their ends into and transversely of the furnacechamber, and a horizontal baffle-plate arranged longitudinally of the furnace-chamber at the point of the bends in said tubes, said tubes passing through said plate, whereby the products of combustion are conducted in a path normal to the lower parts or ends of said tubes and are then returned in a similar path with respect to the upper ends of said tubes, as and for the purpose set forth.

In witness whereof I have hereunto set my hand, this 31st day of March, 1898, in the presence of the subscribing witnesses.

DAVID I JONES.

\Vitnesses:

S. E. DARBY, E. O. SEMPLE.

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