APPENDIX,

REPORT OF A BOARD OF U. S. NAVAL ENGINEERS ON THE BELLEVILLE BOILER OF THE STEAM-YACHT SHEARWATER, AT WOOD'S HOLL, MASS., NOVEMBER, 1887.

In obedience to the order of the Navy Department of the 28th of October ultimo, and in accordance with the instructions of the Bureau of Steam Engineering of the 4th instant, we have made a careful test of the Belleville boiler of the steam-yacht Shearwater, and submit the following report:

DESCRIPTION OF THE VESSEL.

The Shearwater is a steel yacht, built according to the design of Mr. Edward Burgess for Mr. J. M. Forbes, of Milton, Mass. The engine was designed and both hull and engine built by the Atlantic Works, of East Boston, Mass., Mr. James T. Boyd, engineer and superintendent. The boiler, with its attachments complete, was built at the Belleville Works, St. Denis, France, and imported for this vessel.

The principal particulars of the hull are as follows: Length over all, 129 feet; length on load water-line, 108 feet; beam, molded, 17 feet 11 inches; depth from top of keel, 10 feet; crown of deck, 5 inches; draught of water, 6 feet 6 inches; displacement, 115 tons; midship, section, 68 square feet; overhang at stern, 21 feet; stem, vertical above water-line; bar keel of rolled iron, 5 by 13 inches; stern-post and rudder-post forged in one piece, with section, 54 by 24 inches; stem, rolled iron, 54 by 14 inches; the frames are spaced 21 inches between centers, and are of angle iron 24 by 2 by f inches.

Floors are in one piece, 13 inches deep by inch thick under the engine; reverse angle irons, 2 by 2 by inches; keelson on top of floors, 7 by inch plates, with 3 by 24 by inch angles. The plating is run in fair lines, in and out strakes, and is of mild steel; garboard and shear strakes, inch; remainder, No. 3 B W. G. thick, for half of the length amidships, and reduced forward and aft to No. 5 B. W. G.

Stringers on beams are of steel, No. 3 B. W. G., 16 inches wide, and connected to shear strakes with 5 by 24 inch channel-iron. At break of deck on beams, stringers are 16 inches wide. At break in continuation of main deck, stringer is an angle iron, 6 by 3 by inches, riveted to clips on frames and attached to bulkheads. Deck-beams are spaced on every frame and are angle irons 4 by 3 by f inches, with bracket ends 10 inches deep. Those forward and aft of half length are of reduced size. The foreand-aft plates on each side of hatches are of steel, 6 by inches, riveted to deck beams. There are two bilge stringers on each side, 34 by 24 by inches. In addition to breasthook of deck stringer there is one at load line of 4-inch steel plate, fastened to reverse bars by 2 by 2 by inch angle iron, extending over three frames. There is a collision bulkhead forward, and a water-tight bulkhead aft, at forward end of stern-tube, of -inch steel. The coal-bunkers are of -inch steel. The stem, rudder and sternposts, and keel are double-riveted, all other riveting being single. The rudder has a wrought-iron frame plated with -inch steel. The bottom is cemented with Portland cement carried well up into the turn of the bilge.

There are two light masts, 94 inches diameter, 55 feet high, with fore-and-aft rig.

ENGINE.

The engine, designed to develop 220 horse-power, is of the vertical, inverted. direct-acting, compound type, with cylinders of 12 and 25 inches diameter, and 20 inches stroke of piston; working pressure 120 pounds per square inch by gange in high-pressure cylinder. The condenser is of the Wheeler, double-tube type, the circulating water entering the outer tubes and returning in inner tubes of the lower half, then passing through inner tubes and returning by outer tubes of the upper half of the nest. The condensing surface is 440 square feet. The condenser is located

on the port side, opposite the cylinders, with tubes horizontal and fore and aft. It is elevated sufficiently above the engine bed-plate to conveniently place the air and circulating pumps directly underneath it. The pumps are horizontal and direct-acting, the steam-cylinder forward, circulating-pump in the middle, and air-pump aft, the three piston-rods being continuous. The diameter of the steam-cylinder is 6 inches, that of air and circulating pumps 8 inches, the stroke being 12 inches. The circulating water is delivered to a chamber between the two tube-sheets at forward end of condenser. This chamber is divided into equal parts by a partition midway between its top and bottom. The forward part of condenser is dished to form a channel-way from lower to upper half of nest of tubes, for the passage of circulating water. The nozzles for the inlet and outlet of circulating water are on the lower and upper sides of the rectangular box at end of condenser. The tubes are screwed into the tube-sheets at the forward end. The caps by which the outer tubes are closed at the after end are of sufficient size to form supports from shell of condenser for the lower row of tubes and thence upward for all the other rows. The inner tubes are open at the after ends and supported concentrically within the outer tubes by small pins screwed into their sides near the ends. The exhaust steam is delivered to the outside of tubes through an opening in the top of condenser and at the middle of its length, being first passed through a kind of strainer, or "grease-collector," as it is called, which is bolted directly to the nozzle. This grease-collector is a rectangular box containing porous metallic strainers. The condensed steam and air are conveyed by a copper pipe from the middle and bottom of condenser to the air-pump, and thence delivered to a tank above the pump. The feed-water is drawn from this tank and delivered to the boiler by the independent feed-pump on starboard side of engine-room. An injector is connected to main feed-pipe for feeding the boiler whenever required. A second pump is connected to the bilge, sea, and hot well, and to the fire-service pipes, but can not be used to feed

the boiler.

The piston-rods of the main engine are each 24 inches in diameter; cross-heads, 3 by 6 inches; slides, 64 by 12 inches; connecting-rods, 50 inches between centers; crank-pin journals, 5 by 5 inches; crank and line-shafting, 54 inches in diameter at journals. The forward crank-shaft journal is 8 inches, the middle one, 16 inches, and the after one, 10 inches long. The greatest pressure on crank-pins, with steam of 120 pounds pressure in high-pressure cylinder, is 409 pounds per square inch.

The steam-pipe is 34 inches and the exhaust-pipe, 7 inches in diameter. The steamports in high-pressure cylinder are 10 by 14 inches, the opening being 1 inch; those in low-pressure cylinder, 19 by 13 inches, with 1-inch opening. The exhaust-port in high-pressure cylinder is 10 by 3 inches, and in low-pressure cylinder, 19 by 34 inches. Travel of valve, 34 inches. The throttle is a plain slide valve with three ports, 1 by 4 inches each. Both cylinders are fitted with Meyer cut-off valves, with separate eccentrics. The main valve-gear is of the Stephenson type. The cut-off blocks are adjusted by a screw-stem, easily worked from engine-room.

There is a small vertical reversing-engine on the forward and starboard side of bedplate which exhausts into the condenser.

The propeller is a true screw, of cast-iron, 6 feet in diameter and a pitch of 8 feet, the blades being cut away at the ends to give them somewhat the form of a Griffith's blade. The casting is in one piece and the hub only large enough for the requisite strength.

BOILER.

The boiler consists of a system of tubes of equal length joined together by junctionboxes of malleable steel, so as to form a series of flat coils, each of which is connected to the feed-water box or collector C (Plate 1) at the lower end of the coil, and to the steam-drum D, at its upper end. The steam-drum, into which the feed-water is also delivered, is connected with the feed-water collector and a vertical cylindrical vessel, called a sediment-collector, by two outside pipes, E and E', the one on the starboard end leading direct to the feed-water collector.

This arrangement permits of a continuous circulation of water and steam through the tubes to the drum and of the water from the drum to the feed-water collector. Each coil consists of sixteen lap-welded, wrought-iron tubes, 3 inches in outside diameter, and 614 inches long between junction-pieces at the front and back, the tubes being arranged in two vertical rows si le by side. The back junction-boxes are simple U connections, with the centers of the openings for receiving the tubes in the same horizontal plane half-way between the levels of two adjacent front junction-boxes, and have on their upper and lower sides proper projections for supporting them, one above the other, in the required positions. The front and lowest junctionboxes, b, b, resting directly on the feed-water collector, have each four openings for the reception of tubes, one opening in the lower row being blanked off; the other front junction-boxes, a, a, form simple horizontal U connections like those at the back. The tubes in each vertical row are parallel, those in the right-hand row rising gradually from the front to the back, and those in the left-hand row, from the back

to the front. The lower front junction-boxes have two chambers, the upper one forming a U connection; the lower one, which receives the lower end of the last tube, has in its lower side a conical opening, into which fits a conical nipple on the feedwater box or collector C, the joint being made with a thin conical metal washer, a single bolt and nut securing the joint and the junction-box to a projection on the front of the feed-water collector. The upper tube of each set is connected by means of an elbow and a short vertical tube having a flange-joint to the steam-drum. Each set of sixteen tubes is called a "tubular element," eight of these forming the boiler. The whole of each element is heating surface.

On the frout of each front junction-box and opposite the tubes there are circular sight-holes, 24 inches in diameter, for inspection and cleaning. These holes are closed by means of wrought-iron plugs, each held in place by a single anchor or T-head bolt and nut, the joint being made with linen asbestos cardboard.

The junction-boxes are inch and the tubes inch thick, except those in the lower row in direct contact with the fire, which are inch thick.

Each tubular element, 4, 4, is complete in itself and independent, being connected with the other elements only through the feed-water collector below and the steamdrum above. In case of any accident to a tube or tubes of an element, the latter can be readily and quickly disconnected and removed by means of a railway provided for the purpose, the connection holes blanked, and the rest of the boiler used without inconvenience.

The tubes are screwed into the back junction-boxes with ordinary gas-threads and further secured by jam-nuts screwed up hard against the faces of the boxes; at the front ends they butt against nipples, threaded similarly to the tubes, and are held in place by screw-couplings, shouldered against the faces of the boxes and secured by jam-nnts on their backs. By this arrangement, after an element has been removed from the boiler and is accessible in all its parts, any two tubes, connecting in the same back junction-box, may be removed and renewed without disturbing any of the others, a valuable consideration and great convenience in case of repairs.

The eight tubular elements occupy a space 73 by 78 by 50 inches high. The furnace, grate, and ash-pan are directly under the tubes, the bars being 214 inches below the lower tubes at the front and 28 inches at the back end. The ash-pan is 16 and 13 inches below the grate at the front and back, respectively. The furnace is rectangular, the grate-surface being 82 inches wide by 60 inches long, giving 34.17 square feet

of surface.

The feed-water collector C, which extends across the entire front of boiler, just above the furnace doors, and on which the lower front junction-boxes rest, and to which they are connected as before described, is of iron, forged in rectangular section, 5 by 5 inches outside, five-eighths of an inch in thickness, and is connected to the top of the sediment-collector G and to pipe E' by elbows, screwed into the front near the ends, and secured by jam-nuts, similar to those on joints of tubular elements.

Just below the feed-water collector and close to it, there is a small steam-pipe, 8, connected to the stop-valve near the steam-drum, which supplies steam to four cylindrical nozzles, spaced equally across the furnace, for the purpose of blowing steam above the fires. This device is termed "the mixer of gases." Its use with bituminous fires is advantageous, probably from the fact that it tends to keep the outside surfaces of tubes clean, thus securing better draft; but, with anthracite fires, its use tends to, and if continued sufficiently long, it is said, will extinguish them.

The tubular elements, fire-box, and ash-pit are inclosed by a rectangular casing (at the sides and back) of boiler-iron, with a double arched covering forming the uptake. The casing in front is formed by two large doors, O, extending from the feedwater collector to the top and between the side castings. The furnace-doors or fronts are of wrought iron with double shell and extend from the feed water collector down to the level of the front bearing-bar. There are two doors, each 33 inches wide by 13 inches high. The ash-pit doors, s', are hung horizontally on two pivots at half their height in such a manner that they may be used as dampers or wholly removed, as may be desired. The boiler casing, from the top down to the level of the upper side of front junction-boxes, is 83 inches wide by 78 inches deep outside, and consists of a double shell stiffened by angle-irons, the inclosed space, 4 inches wide, being filled with ashes packed hard. Below the above level, down to the plane of the gratebars, the two sides consist of single thicknesses of plate-iron, stiffened by angle-irons and lined with fire-bricks; this lining, for 13 inches down, being 11 inches, and, for the rest of the way, 10 inches thick. At the back, the double shell casing extends down 14 inches further than at the sides; from its end, the single casing, lined with fire-bricks from 13 to 11 inches in thickness, extends to the box mentioned below. On the top and front of this back lining there is a single course of fire-bricks, put in place after the tubular elements are put in, and adjusted to support the back junetion-boxes at the required height. The sides and back of the ash-pit are inclosed by rectangular boxes open at the bottom, those at the sides being 10, and those at the back, 12 inches wide. These boxes are made of boiler-iron and their tops, which are

m the plane of the grate-bars, form shelves on which the brick-work rests. The casing from the beginning of the fire-brick lining down to the bottom of the ash-pit is larger than that above, being 1024 inches wide by 81 inches deep outside.

The French grate-bars supplied with the boilers are of wrought iron, inch thick and 4 inches deep, and are described as being alternately flat and undulated, with spaces between them of the form of elongated triangles. The advantage is claimed for them of maintaining a sufficiently low temperature to prevent the adherence of clinker, the bars being, therefore, easily kept clean. These bars were not used during the trial, ordinary cast-iron ones being substituted, these having larger air spaces and the experience of the engineer on board having demonstrated also that these were easiest kept clean.

BB are fusible plugs. PP are movable partitions of cast-iron placed between the tubes. Q, sheet-iron obstruction, placed over elements.

BOILER ATTACHMENTS.

These attachments, generally described as the Belleville patents, are as follows: "The collector-purifier of steam and feed-water," which we call the steam-drum; tho "sediment receiving-chamber," or, sediment-collector; the automatic feed-water regulator; the "general steam separator," with its automatic purge; the "steam-pressure regulator," or reducing valve; and the special feed pump.

The internal arrangement of the steam-drum, as applied on board the Shearwater, is entirely different from that generally described.

The general steam separator with its automatic purge has not been applied to the Shearwater and is not shown.

The steam-drum D D, used on the boiler tested, was made complete in France, and its interior is, therefore, entirely inaccessible for measurement. From what could be seen and felt through the hand-holes, the drawings on plate 1 have been made, which clearly show the arrangement, although not accurate in internal dimensions. From this arrangement it will be observed that the centrifugal theory is ignored.

The drum is 77 inches long and 19 inches in external diameter, with a double chainriveted lap seam and flanged heads, secured by single riveted seams. Its interior is divided into three nearly equal compartments, Z, T, and N, by diaphragm plates, x, y, and 8, extending its whole length, bent and riveted together along a line near the axis. A shelf, e, of channel-iron near the top of the compartment Z, is secured to and extends the whole length of the drum. The feed-water is delivered at g in the middle of the length of the drum, and above the shelf e. The diaphragmplate y is curved, as shown, extends beyond the junction seam towards the shelf e, and to it is secured a second curved plate, r, by means of light Z pieces, the two curved plates together forming guides for the steam coming from tt. Compartments Zand T communicate through the triangular openings U and U' cut from plate I, as shown. Compartments N and T communicate through the long, slender drypipe r, which is rectangular in section and extends about two-thirds the length of the drum. A copper drain-pipe, F, with a branch to each end of the drum, connects the lowest part of compartment N with the sediment-collector. Steam is taken from the

top of N and at the middle of its length, through a narrow port, about 14 by 6 inches, without internal pipe, and led to the stop-valve on the right and safety-valve on the left side, as shown." From the bottom of Z, pipes E and E', leading to the sedimentchamber and feed-water collector, connect through the heads.

The manner in which the drum operates is supposed to be as follows: Steam is delivered into Z through t, t, and directed by the guide-plates towards the shelf e, where it thoroughly mixes with the feed-water and heats it sufficiently to precipitate the lime salts. The steam escapes through the triangular openings U and U', into T, and thence through the dry-pipe and N into the main steam-pipe. The water and sediment fall to the bottom of Z and through the pipe E into the sedimentchamber, and through the pipe E' into the feed-water collector direct.

The sediment-chamber G is a cylindrical, wrought-iron drum, 35 inches long and 104 inches in external diameter, placed vertically on the port side and on front of boiler, the pipe E being connected to its upper head. On its side, near the upper end, is the connection to the feed-water collector, and at about one-third its height from the bottom is a cock through which the sediment is blown.

The automatic feed-regulator is arranged to maintain the water level at a constant height and is placed in the feed-pipe M M (Plate 1) near the end of the steam-drum, and between it and the graduated check-valve and cock J.

Plate 2 shows the automatic feed-regulator in detail. The stand-pipe K (see Plate 2), connected at the top with the steam and at the bottom with the water space, has on its side the glass water-gauge and within it the float X, which, through the interior rod and lever l and outside lever E, actuates the conical regulating valve V. The tension of spring Z on the counterpoise is steady, and the weights Q so propor

tioned that each one will cause a variation of one inch in the water level. The valve Vrises with the water level, thus reducing the feed-water supply. Valve Ris simply a second check-valve in the feed-pipe y (Mon Plate 1) above the hand check-valve J. The feed-water is delivered to drum through W.

The theory of the regulator is correct; but, like the automatic purge of the general steam separator, there seems to be an unnecessary complication for the service to be performed. We think that in time this would seriously interfere with its successful working, although during the trial its working was perfectly satisfactory.

THE STEAM-PRESSURE REGULATOR.

In order to have a sufficiently high temperature in the steam-drum to precipitate all the calcareous salts held in solution in the feed-water, the pressure must be maintained there above 120 pounds per square inch by gauge. To permit this and the use of a lower pressure at the engine, the special reducing valve, shown at fig. 2, plate 2, was devised by Mr. Belleville. The chamber A contains a cylinder in which works a piston-valve. Attached to the valve is a plunger, C, which passes through a stuffingbox above and into a guide still higher up. Near the top of the plunger is the crosshead b, to which are attached four spiral springs, F, F, F, F. These springs extend down, outside of the chamber and below it, to a second cross-head, b', which may be raised or lowered by a screw-spindle and hand-wheel, thus diminishing or increasing the tension of the springs. The arrows show the direction of the steam; A B, in the elevation, being the axis of steam-pipe. The piston-valve closes the ports until tension is put on the springs, when it opens them and allows steam to enter 4. The pressure tending to push the valve up acts on an area equal to the cross-section of the plunger and is balanced by the tension of the springs. By varying this tension the steam-pressure at the engine may be varied at will.

THE SPECIAL BELLEVILLE FEED-PUMP. "

In a boiler of such small water-capacity as the Belleville, where the feed supply must be continuous and variable in quantity, special provision is required. For this purpose, the automatic feed is designed, but its operation reacts on the pump, affecting its speed, and if the flow of water were sufficiently reduced, would be liable to stop it. To obviate this difficulty, a special pump has been designed, but its principle of action is not novel in this country, it being almost identical with that of the original Worthington pump. In this pump, the pressure on the water piston is relieved just before the completion of the stroke at each end, thus allowing the full force on the steam piston to move the valve during the rest of the stroke. The details by which this is effected are, however, different. In the Belleville pump, there is a curved lever at each end of the water cylinder, a projection on the lever forming the reliefvalve.

The coal bunkers of the Shearwater have a capacity of 14 tons, are situated on each side of the boiler and fire-room, and extend from the forward athwartship boilerbulkhead to 6 feet 6 inches abaft the boiler front, a door on each side giving.access to them.

The engine, boiler, coal bunkers, and fire-room occupy the entire width of the vessel and a length of 22 feet 4 inches; 7 feet 2 inches of which is boiler space, 8 feet, fire-room space, and 7 feet 2 inches, engine space.

There are two tanks forward, of a combined capacity of about 1,700 gallons, from which the waste of fresh water in engine and boiler is made up.

The smoke-pipe is 31 inches in diameter and 20 feet high above uptake, or 29 feet above grate-bars.

WEIGHTS.

Most of the weights were furnished by the Atlantic Works, East Boston, the rest being computed:

Pounds.

* The weight of water put in boiler to working level during trial was 2,100 pounds by measurement.