the bad coal, and the indifferent stoking combined, make it absolutely necessary that the boiler-power should be larger, in proportion to the size of the engine, than would be required when these unfavourable conditions have not to be contended against. The furnace and combustion-chambers should be as large as can be got into the boiler; the funnels should be of a considerable height, in order to ensure a good draught; the funnel-area about that of the grate, and the heating-surface not less than from 4 to 4 square feet per indicated HP. With these proportions a good economical result may be confidently expected.

The Paper is accompanied by seven tracings, from which Plate 7 has been prepared, giving details of line drawing, Figs. 1; general arrangement, Figs. 2; midship section, Figs. 3; side girders and bulk-heads, Figs. 4; "Chopper," Figs. 5; engine, Figs. 6; boiler, Figs. 7.

[APPENDIX.

APPENDIX.

SPECIFICATION FOR HULL.

General construction of proposed steel steamer. Length, 2623 feet; beam, 35 feet; depth at centre, 10 feet 9 inches to top of deck beams.

One longitudinal central and seven transverse bulk-heads riveted to skin of vessel. Top sides of vessel for about 87 feet amidships to be carried up to upper or coolie deck.

Longitudinal bulk-head to extend from collision bulk-head forward to bulkhead No. 7 aft, dividing the vessel in two portions. To be made water-tight, and carried from skin of vessel at keel-plate to above line of deck, forming one continuous line of plating, composed: bottom, inch; top, inch; and centre perpendicular plates, inch. The upper portion of longitudinal lattice-girder is to be formed of two 2 inches by 24 inches by inch angles riveted to a plate 9 inches by inch, and covered with a rider plate 9 inches by inch, and 6 inches angle-lug fastenings riveted to each upper deck beam, and from this plate for about 138 feet are to be secured angle-bar attachments 2 inches by 24 inches by inch. Plating of transverse bulk-heads, bottom, inch; remainder, inch, stiffened with 2 inches by 2 inches by Keel-plate, for 30 feet long at ends, to be inch; remainder, inch. Skin plating between engine bulk-heads, inch; throughout bilge and sheer-strakes, inch; remainder, inch. Covering-plate at centre of vessel for 150 feet, inch; remainder, inch. Frames spaced throughout, 2 feet 6 inches, 3 inches by 2 inches by inch. Main-deck beams, one on every frame, 4 inches by 24 inches by inch.

inch, and sides

inch angles.

Upper-deck beams spaced 2 feet 6 inches, 3 inches by 24 inches by & inch. Camber of both decks, 9 inches. Floors spaced 2 feet 6 inches throughout by 10 inches deep by inch thick.

Reverse angle-bars, 24 inches by 24 inches by inch, in engine and boilerspace to be riveted on both sides of the floors; remainder throughout, 2 inches by 2 inches by inch on one side only.

All reverse frames to be carried well up turn of bilge. Cants at sides to support upper-deck beams, 3 inches by 24 inches by inch.

One intercostal keelson to be placed on either side of longitudinal bulk-head, continuing for about 180 feet amidships, finishing off at the ends of the vessel with two angles back to back secured to reverse frames of floor, angles, 24 inches by 24 inches by inch; intercostal plating, 12 inches by inch. Nine of the 10-inch floors in centre of engines on either side of the vessel continued up sides to under side of deck. Covering-plate with the reverse angles to be continued upon edge of plates. Two intercostal shelf-pieces 12 inches wide, angle-bars outside riveted to sides of vessel for a distance of 40 feet, and spaced 3 feet 9 inches.

Every third frame, for about 170 feet amidships, to be carried up on each side of longitudinal bulk-head to meet deck beams, and riveted through bulkhead.

Gusset-knees on every deck beam, both at longitudinal bulk-head and shipside, for the whole length of the central longitudinal bulk-head; and diagonal angles between each frame riveted one to either side of bulk-head.

On upper side of bilge-strake are to be two angles back to back, secured with angle-lugs, riveted to each frame of the vessel. Angles, 24 inches by 24 inches by inch; gussets, 12 inches by inch; stem and stern-posts, 6 inches by 1 inch; top deck stanchions on every second frame.

Main deck to be of teak, 6 inches by 24 inches, in lengths not less than 20 feet. Upper deck to be of teak, 6 inches by 14 inch, in lengths not less than 20 feet. A. J. BOLTON,

Superintendent Engineer, I. G. S. N. Co., Limited.

Calcutta, 21st June, 1889.

GENERAL SPECIFICATION FOR FOUR BOILERS.

Specification for four marine multitubular steel boilers for two sets of engines to indicate 1,200 HP.

Four marine multitubular steel boilers to Board of Trade requirements for a working pressure of 100 lbs. per square inch. Each boiler 12 feet 5 inches diameter, to contain two of Fox's corrugated furnaces, 3 feet 9 inches mean diameter, with one combustion-chamber common to both furnaces; width across combustion-chamber to be 30 inches. Diameter of tubes, 3 inches outside. No. 8 B. W. G. by 7 feet, spaced 4 inches centre to centre, in vertical rows. Total heating-surface not less than 5,400 square feet.

Boilers to fit in the space as shown in drawing, leaving room for stoking, and each boiler to have one funnel not less than 3 feet 7 inches diameter, and 40 feet above firebars. Funnels to be hinged where marked on sketch. Boilers to be fitted with McNeil's patent man- and mud-hole doors. Smoke-boxes and doors. Uptakes and air-casings. Firebars in two lengths. Fire-bearers. Dampers for funnel and ash-pit. Boilers to be fitted with Dewrance's gauge-columns and test-cocks, with all necessary pipes and cocks for attachments to boilers. Blowoff, scum and other cocks. Patent spring safety-valves with casing gear, and one spare spring. Complete working drawings of boilers, showing seatings required to clear butts and seams. Boilers and all works to be of the best materials and workmanship, and made under the supervision of the Board of Trade, and to be tested by water to a pressure of 200 lbs. per square inch.

The four boilers, each 12 feet 513 inches diameter, complete with uptakes, funnels, &c., &c., must not exceed 90 tons in weight. Actual weight of boilers complete to be forwarded as early as possible.

GENERAL SPECIFICATION FOR TWO SETS OF ENGINES.

Specification for two sets of paddle diagonal surface-condensing compound engines, for the India General Steam Navigation Company, Limited, to indicate 1,200 HP.

Two sets of compound surface-condensing, feathering, paddle-engines, complete in every detail, ready for working, to include the usual spare gear, as per Board of Trade list-savealls, spanners, eye-and-hook bolts, sets of taps and dies, complete sets of engine-room telegraphs, indicators and indicator-gear complete for taking diagrams.

Type, diagonal compound, constructed for a working pressure of 100 lbs. per square inch, and piston speed not less than 400 feet per minute, and 1,200 indicated HP. Slide-valves, arranged and adjusted so that high- and low-pressure cylinders shall indicate the same power, equalising twisting strain on both engine-cranks. All bearings, connecting-rods, top and bottom ends, and main bearings, to have extra large surfaces. Main bearings may be run with best white metal over brass. Connecting-rod top and bottom and guide brasses should be of phosphor bronze. Each set of engines supplied with Dewrance's. or other good make, sight feed-lubricators, in addition to all other necessary oil-cups and cocks requisite for lubricating purposes, fixed in their respective positions.

All parts of the engines that may require overhauling and adjusting from time to time must be arranged to be easy of access.

Air- and circulating-pumps placed vertically; surface condensers to have ample tube-cooling surface adapted for a sea temperature of 90°, and to maintain abundant feed-supply, irrespective of the auxiliary feed. Condensers placed athwartship, arranged with necessary appliances for working either common jet or bilge injection. Condensers, before being placed on board, must be tested to 30 lbs. per square inch; all necessary air-vessels, air-pipes, relief-valves, &c., to be fitted. Circulating inlet at the bottom, and outlet on the top, of condenser. Engines so placed to admit of space to draw condenser tubes.

Feed- and bilge-pumps of sufficient capacity with all necessary air-vessels-relief-spring, test-cocks, &c., to be supplied.

High-pressure cylinder, 28 inches in diameter; low-pressure, 50 inches in diameter. High-pressure cylinder fitted with single-ported, and the low-pressure with a double-ported valve, all ports and passages, induction and eduction, to be of large areas. Cylinders not jacketed, but very carefully felted and lagged with best Honduras mahogany, neatly secured with brass-polished stout hoops securely fastened with screws to barrels of cylinders. All necessary escapevalves, guards, and cocks to be fitted.

Stroke of engine, 60 inches.

All shafting, piston- and other rods, to be of the best quality of steel, supplied by one of the most approved manufacturers in the United Kingdom, who make shafting a speciality.

Each set of engines supplied with steam reversing-gear, so arranged that in case of need the engines can be quickly manipulated by hand, and all gear necessary for working the engines should be conveniently brought together on the engine platform, so as to be easily handled by one man.

All necessary sea-cocks and valves on skin of vessel to be supplied of the most modern design. All necessary copper and other piping, faucets, bends, elbows, &c., &c., required for the various connections from high-pressure cylinder to boiler's stop-valves, to be supplied. Also feed- and bilge-pumps, ash pipes, exhaust and discharge pipes, &c., with all cocks and valves necessary to enable the engines to work under steam when placed on board the ship in Calcutta. Main steam-pipe between boilers to be overhead, with connections to highpressure cylinders.

Two good powerful donkey-engines, capable of supplying four 12 feet 5 inches diameter boilers with abundance of feed, against a working pressure of 100 lbs. per square inch, and, in addition, arranged to work on deck as fire-engines.

A good hand-pump for filling boilers to be fitted; compound vacuum and steam-gauges of best make required for each engine.

Paddle-wheels to be of the most modern type as regards design of feathering and other gear. Diameter at centre of axis of floats, 15 feet; number of floats

Papers.

on each wheel, eight; size of each float, 12 feet by 3 feet; total area of float surface, 576 square feet. All bushes of gun-metal, all pins of steel, bushes bored, and pins, &c., turned. The scantlings of wheels to be strong. All boltholes rimered, and bolts carefully fitted. Wheels carefully and well put together.

All work as regards engines, piping and wheels, must be of the highest-class workmanship and finish, and well painted. To be carefully marked for erection on board the vessel in Calcutta, well and carefully packed, and contents of each package noted in invoice. Each set of engines to be of different colours. Engines to be constructed as light as possible consistent with ample strength. Tracing supplied showing sheer draught plan of steamer, and space available for engines and boilers. Height of centre of shaft, 10 feet 10 inches from bottom of vessel. Speed of vessel, 15 miles per hour. Successful contractors will submit as early as possible their arrangement for engine and boiler seatings, which must be made of as light materials as possible.

Position of all sea-cocks on skin of vessel to be carefully marked. Time of delivery in Calcutta to be stated. Engines and boilers placed so that vessel will float on an even keel.

Omissions: Any omission in this specification so far as regards the requirements of engines, and all connections from the engines, as well as from engines to boilers, will not be regarded as an omission, as it must be distinctly understood that the contractor has to deliver the machinery in Calcutta complete in each and every detail, ready, when placed on board the ship, to raise steam.

Engines and paddle-wheels, complete for service, must not exceed 150 tons in weight. Actual weight of engines complete to be forwarded as early as practicable.

21st June, 1889.

A. J. BOLTON, Superintendent Engineer.

Note.-400 feet piston speed is given to show what strains the engines should be designed to stand in conjunction with the 100 lbs. pressure per square inch.

-A. J. B.