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propelling machinery consists of two sets of engines of the triple-expansion inverted type of Messrs. Laird Brothers' design. The screw propellers are four-bladed, the blades and bosses being of manganese bronze. The boilers are eight in number, single-ended, of the cylindrical returntube type. Each pair of boilers is in a separate water-tight compartment, with independent coal supply, separate access to and from main deck, etc. There are two distillers with circulating and distributing pumps, four Admiralty type main feed and four auxiliary feed pumps, of ample size to supply the whole of the boilers at full power, and four double cylinder double-acting_bilge and fire pumps, and a pump for pumping out the drain tank. The several pumps are connected to the large drain pipe and double bottom. General ventilation is secured by two large fans 72 in. in diameter, and eight fans 72 in. in diameter supply the forced draught for the boilers. The Mars illustrates the advantage of building these large battle-ships in dock in preference to building them on a slip and launching them, as she carries with her all her citadel armor, most of the barbette armor, and four casemate fronts; indeed, all the armor-plating would have been completed had it not been for the press of work in Sheffield rendering it impossible for the armor-plate manufacturers to make delivery as early as required. The main boilers are on board, with all mountings and connections complete, ready for steam, save the funnels. The whole of the auxiliary machinery is also in place, and pipes and connections fitted, and the main engines are fully two-thirds erected on board, so that the vessel, as floated out from the building dock, is in a far more advanced state than would have been the case had she been launched in the ordinary way. The order for the Mars was given exactly two years ago on March 26, and the steel and other materials were obtained and her keel laid on June 2, 1894, practically 22 months to date. When ready for the pennant in six or eight months, she will have a complement of 750 men.

THE RANGER.

The Ranger is the third and last of three torpedo-boat destroyers which Messrs. R. and W. Hawthorn, Leslie and Co., of Newcastle-on-Tyne, have built for the Admiralty. On April 1 she made her official full-speed trial off the mouth of the Thames, the particulars of which are of interest. The vessel, like her sisters the Sunfish and the Opossum, is 200 ft. long and 19 ft. wide. The draught on trial was 5 ft. forward and 8 ft. 11⁄2 in. aft, at which the displacement was 278 tons. These figures refer to the commencement of the trial. Naturally as coal was burnt the displacement and draught decreased. The trial was for the usual three hours, six runs being made on the Maplin measured mile, the mean speed for the whole distance being 27.172 knots. The Ranger has three-stage compound engines, having cylinders 181⁄2 in., 28 in., and 42 in. in diameter, the stroke being 18 in. The cooling surface in the condensers is 3000 square feet. The boilers are of the Yarrow type, and are eight in number. Each has a grate area of 21 square feet, and a heating surface of 1063 square feet. On the trial the average steam pressure in the boilers was 194 lbs. to the square inch, the air pressure in the stokeholds 3.07 in., and the vacuum 24.2 in. The revolutions averaged 348.25 per minute. The aggregate horse-power for both sets of engines was 4055 indicated. During the six runs on the mile the speed was 27.093 knots, which, it will be seen, was less than that for the whole distance. This is a cir

cumstance that has before occurred on the trials of destroyers having water-tube boilers, but which we do not remember ever to have observed in the case of flame-tube boilers. It may doubtless be taken as a testimony to the superior endurance of the former class of steam generator, or perhaps one should say to the greater ease with which the best designs of water-tube boilers are fired, and, therefore, to the superior endurance of the stokers. As is well known, the human factor" is almost as of great importance as the "machine factor" in the trials of these small quick-running craft.

THE HAUGHTY.

The torpedo-boat destroyer Haughty, which was built by Messrs. William Doxford & Sons, Limited, of Sunderland, and fitted with eight of Yarrow's water-tube boilers, on her official trials made 27.949 knots as the mean on the six measured-mile runs, the engine revolutions being 371.74. The speed registered on the three hours' trial was 27.525 knots. The revolutions were 362.3, with an indicated horse-power of 4224, steam pressure in the boilers 188 lbs.

Mr. Beauchamp Towers' ingenious apparatus for providing a steady platform at sea has been fitted by Sir W. G. Armstrong & Co. to the torpedo-boat destroyers Swordfish and Spitfire, and is also to be supplied to a Chilian cruiser now building at Elswick. The apparatus, it will be remembered, depends on the fact that a gyroscope tends to maintain an invariable plane of rotation. In practice, a gyroscope is arranged to rotate about a vertical axis. As the vessel rolls, the gyroscope, maintaining its original plane of rotation, tilts relatively to the vessel, and this relative motion is used to control the supply of water to a set of four hydraulic cylinders connected to the steady platform in a suitable manner. In practice it is found that with it a search-light on a small vessel can be kept quite steady on a mark even in a heavy sea.

THE RENOWN.

The first-class battle-ship Renown, which has been built at Pembroke, made her full-speed contractors' steam trial in the Channel on April 6. The eight hours' natural draught trial was run on the 27th of March.

The Renown is a particularly interesting ship at the present time, as she is to be the prototype of the five new battle-ships which are in this year's naval programme. The vessel is 380 ft. long and 72 ft. wide, and is designed to have a displacement at load draught of 12,350 tons. The engines are of the three-stage compound type, having cylinders 40 in.. 59 in., and 88 in. in diameter by 4 ft. 3 in. stroke. The high-pressure engine has a piston valve, the ordinary flat valve being used for the intermediate and low-pressure engines. The propellers are of gun-metal, and are 16 ft. 6 in. in diameter and 21 ft. mean pitch. There are eight singleended return-tube boilers, each 16 ft. 6 in. in diameter and 10 ft. 3 in. long. They have each four furnaces. The total grate area is 793 square feet, and the total heating surface 24,840 square feet.

For the eight hours' natural-draught trial a very early start had naturally to be made. The conditions were fairly favorable to the ship, the wind being of a strength from 3 to 4 and the sea moderate. The trial ground

the coast far enough out to be in deep water. The mean results were: 507 Steam, 143 lbs.; vacuum, starboard 26.9 in., port 26.9 in.; revolutions, starboard 97.5, port 98.2; indicated horse-power, starboard 5233, port 5475 -total, 10,708; speed, 17.9 knots. Messrs. Maudslay, Sons & Field, the makers of the machinery, were responsible for an indicated horse-power of 10,000 only on the natural-draught trial, but more than once during steaming the engines easily attained 11,000 indicated horse-power, while the mean was 708 in excess of the stipulated power. The mean speed was exactly I knot more than her designers anticipated that the vessel could attain on her natural-draught trial, and knot more than it was estimated she would steam under forced draught with 12,000 indicated horse-power. We now turn to the full-power trial of April 6. The ship had been taken into the Hamoaze after her natural draught trial, and in steaming out of the very crooked channel leading into Plymouth Sound gave unmistakable evidence of her handiness, both engines being kept going steadily ahead, the vessel swinging to her helm with remarkable promptitude. Such a performance was highly gratifying to those who remember the somewhat erratic performance of certain armor-clad ships of past times. The ship having passed out of the Sound into the Channel, hatches were soon closed and the trial commenced at 12.12 P. M., the course being first to the westward. The day was all that could have been desired for a trial, the wind being no more than a gentle breeze and the sea quite smooth. The engines were opened out full, there being no difficulty in keeping steam, in fact, the safety valves were lifting part of the time.

As will be seen, the air pressure was quite moderate, averaging about in., and though the engines developed 901 units above the contract horse-power, the engineers are confident that considerably more power could be obtained were the slides altered and the full air pressure allowed by the Admiralty regulations taken advantage of. How far this would result in additional speed is, of course, an open question, but the ship seemed to pass through the water so easily at the highest rate of steaming that possibly a good deal more might be got out of her if considered desirable.

The following are the mean results of the half-hourly observations on the full-speed trial: Steam pressure in engine-rooms, 145 lbs.; vacuum, 27.3 in.; air pressure in starboard boiler-rooms, .6 in.; in port boiler-rooms, .8 in. Revolutions of starboard engines, 101.6 per minute; of port engines, 106.5 per minute. Mean pressures per square inch of piston: Starboard engines: High-pressure cylinder, 67 lbs.; intermediate cylinder, 27.8 lbs.; low-pressure cylinder, 13.5 lbs. Port engines: High-pressure, 63.6 lbs.; intermediate cylinder, 28.7 lbs.; low-pressure cylinder, 13.4 lbs. horse-power, starboard engines, high-pressure, 2206; intermediate cylinder, 1993; low-pressure, 2141-total, starboard, 6340. Port engines-total, port, Indicated 6561. Total indicated horse-power, 12,901, or 901 in excess of the contract. The engines worked well and steadily throughout the trial. The speed, as taken by cross bearings from points on the coast, was 18.75 knots for the whole distance steamed, the vessel making several turns and running up and down so as to equalize the influence of the tide.

A subsequent thirty hours' consumption trial shows that her most economical rate of steaming is three-fifths of her full natural draught engine power, at which she made a speed of over 15 knots, the vessel being ballasted to give her the same draught, 26 ft. 9 in., as she will have

when in commission fully completed for sea service. The mean results of the trial were: Steam, 137 lbs.; vacuum, starboard, 27.8 in.; port, 26.8 in.; revolutions, starboard, 85; port, 88.6; indicated horse-power, starboard, 3143; port, 3044; total, 6187; air pressure, nil; speed, 15.3 knots. The coal consumption was 1.88 lb. of coal for each indicated horsepower per hour; the coal stowage capacity at load draught is 800 tons.

THE DESPERATE.

The official trial of the torpedo-boat destroyer Desperate was successfully made on April 16. Hitherto contractors have been allowed unlimited coal and horse-power, no restrictions being placed upon them, so long as they attained the required speed with the specified weight on board. In the case of the 30-knot vessels, not only was an additional speed of 3 knots over that of the former number demanded, but it was also laid down that the coal consumption on the full-power trial should not exceed 21⁄2 lbs. per indicated horse-power per hour, if the minimum load of 35 tons were carried, the load penalty being 2 tons additional for every tenth of a pound that the coal consumption exceeded the 21⁄2 lbs. It is well known that the very high speed of these little vessels has hitherto been largely due to a total neglect of the economy question when running at the highest speeds, although the boats were fairly economical at lower powers. The practice was perfectly defensible, because the boat would not be expected to run at her highest speed, either in war or peace times, but for short periods, and then a few pounds of coal would not be of great importance unless the circumstances were altogether exceptional. Experience shows, however, that the conditions were not impossible. The trial was run on the Maplin mile in rough weather. A weighed quantity of coal, estimated to be sufficient to take the boat down river to the trial ground, was placed in bags, whilst in the bunkers there was a quantity of coal estimated to be sufficient for the three hours' trial. On the vessel reaching the mile, and the trial commencing, there remained over a ton of coal still in the bags, and this was of course put by, so as to be beyond the reach of the stokers. At the termination of the three hours a considerable quantity of coal remained. The bunkers were sealed up by the Admiralty officials, and immediately on the return of the boat the quantity was ascertained. The result of the trial was that the indicated horse-power was 5620, and the coal consumption 2.491 lbs. per indicated horse-power per hour. The speed on the whole run was 30.112 knots. The full load of 35 tons was of course carried. The steam pressure averaged 209 lbs., the vacuum 24 in., and the revolutions 398 per minute. The air pressure for draught averaged 31⁄2 in. on the water gauge, and the coal burnt was about 80 lbs. per square foot of grate per hour. As our readers are aware, the Desperate has made previous trials, and on one occasion, with a reduced load, she made on the mile a speed of just over 31 knots, whilst on another occasion she steamed 30.46 knots with full load. On both these trials, which were of a preliminary nature, the coal consumption was above the standard. Messrs. Thornycroft have since fitted an arrangement by means of which air at 10 lbs. to the square inch pressure is introduced at the front about 2 ft. above the fire, there being 9 or 10 jets to each furnace. This was found on the trial to give very good results, the quantity of smoke being much reduced, and the flame, which

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from the chimney tops. The latter feature in itself is one of great importance in torpedo vessels. It will be seen from what has been said that Messrs. Thornycroft have scored still another success with their most recent boat. Certainly to drive a boat 210 ft. long at a speed of 30 knots on so light a consumption as that stated is a remarkable thing, even in these days of phenomenal speeds. The low fuel consumption bears out the consumption trials made by Professor Kennedy some time ago, when the water evaporated by the Thornycroft boiler was measured. The Admiralty have this week placed with this firm a further order for three more 30-knot destroyers and one of 32 knots. The latter will be a larger vessel than the Desperate class, and will of course have more power; there will be four boilers in place of three. The other three boats will doubtless be sister ships of the Desperate now that that vessel has done so well on trial.

THE HANNIBAL.

The battle-ship Hannibal was launched from the Pembroke dockyard on April 28. She belongs to the same class as the Majestic and Magnificent. Her keel was laid on May 1, 1894. The machinery, of 12,000 indicated horse-power, to give a speed of 171⁄2 knots, is being supplied by Messrs. Harland & Wolff, Belfast.

THE HUNTER.

The torpedo-boat destroyer Hunter, built by the Fairfield Shipbuilding Company, had a three hours' trial of her machinery at Portsmouth on May 17. Her draught was 5 ft. 1 in. forward and 7 ft. 5 in. aft. The steam in boilers was 195 lbs., with a total indicated horse-power of 4245. She gave a mean speed of 27.245 knots during six runs on the measured mile. The trial was regarded as highly satisfactory.

THE ARROGANT.

The Arrogant, fleet cruiser, was launched from Devonport Dockyard on May 26. She is the first of four of the same type now under construction from the designs of Sir W. H. White, Director of Naval Construction, the others being the Gladiator, building at Portsmouth; the Vindictive, at Chatham; and the Furious, at Devonport. In size they are a medium between the second-class cruisers of the Astræa class and those of the Talbot type, and in several respects they differ from any cruisers yet built. The principal dimensions of the Arrogant are: Length, 320 ft.; breadth, 57 ft. 6 in.; mean load draught, 21 ft.; displacement, 5800 tons. Rapid progress has been made with the construction of the Arrogant. Her keel was laid on June 10, 1895, and she was pushed forward so expeditiously that she might have been launched two months ago had her underwater fittings been ready. The engines are of the twin-screw, triple-compound, vertical inverted cylinder type, and are guaranteed to develop 10,000 indicated horse-power. They are placed abreast of each other, in separate engine-rooms, divided by a fore-and-aft water-tight bulkhead. The high-pressure cylinder has a diameter of 26 in., the intermediate of 42 in., and the low of 68 in., while the stroke is 39 in. Other dimensions of interest are: Connecting-rod centers, 6 ft. 6 in.; piston-rod diameter, 74 in.; crankshaft diameter, 1334 in. external and 734 in. in