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MARINE REVIEW. ue Early Reminiscences, Harly in May, 1844, the. steamboat Rochester departed from the . foot of. Main street, Buffalo, bound for Chicago. Her crew consisted in part as follows: Thomas P. Folger, master; Harry Weishum, mate; William McGee, engineer; O. H. P. Champlin, clerk; Bartley Logan, steward, and the writer in a minor capacity. During his mechanical work, Engineer McGee had constructed a small steam whistle from plans described in the Scientific American, and which he attached to the boiler of the Rochester, more for the novelty thereof than for its utility. While the boat was moored at the foot of Main street the whistle was sounded, the first to give voice on the Great Lakes. Prior to the advent of the whistle large tolling bells were hung above decks on all lake steamboats, and which in a manner sup- plied the present uses of the steam whistle. On the passage up the lakes McGee's noisy little stranger was sounded to many ears curious of its significance, and in one instance, therefore, nothing but the determined intervention of mutual friends prevented a serious encounter between two stalwart men. During the winter preceding, Captain C. L. Gager had recon- structed the steamboat General Porter into a propeller, and between him and Engineer McGee, an old feud existed. A few miles below Mackinaw the Rochester overhauled and passed the General Porter and at this time McGee blew his whistle defiantly and persistently. The steamboat landed at Mackinaw as also did the propeller, when Captain Gager appeared on the wharf loudly denouncing the man who so in- sultingly "squawked that thing at him." McGee was prompt to as- sume the responsibility, leaping onto the wharf with fierce determina- tion. Then came the resolute intervention preventing war, and thus was demonstrated the utility of the steam whistle on the Great Lakes --and its inauguration without bloodshed. A Detroit vessel owner, in recalling the sailing days of Capt. Har- vey Pheatt, mentioned his manner of loading fuel at the South Mani- tou when sailing the side wheel steamer Forest City in the 50's. The island had a single dock at which the steamer could load, but the beach ran into 20 feet of water so abruptly that timber could not be found on the island long enough,to be made into spiles for the support of the dock at that depth, so it was built out to the edge and they let it go at that, not being willing to go to the expense of cutting the timber elsewhere and rafting it. The Forest City would come up as closely to the dock as she dare under a good head of steam and speed. When near the north end Pheatt would port his wheel hard and drive her nose up into the sandy beach. This would bring her after gang- way pretty close to the dock, and into this gangway the deckhands would shoot the sticks of wood. When she had enough aboard to carry her to her destination it would be found that the wood had loaded her down enough to enable her to back off easily. Otherwise the ut- most power of her engines would have been necessary to back her off, and then, perhaps, she would have gone aground again stern first. The Teutonic arrived in Liverpool on Monday, and on Wednes- day she was equipped with her entire armanent of eight large and eight smaller rapid fire guns ready for use to take part in the naval parade at Spithead: The time taken up in equipment was forty- eight hours. Had war been iminent, it is probable that the time could have been shortened one-half, and the Teutonic would have been put in readiness for sea, bristling with a formidable armament in a single day. She could then set out to destroy the merchant marine of a hostile nation, to enforce a sudden blockade, or to assist the regular fleet. In other words, an ocean greyhound like the Teutonic may come into port one day as a merchant ship and leave port the next day equipped as a cruiser and ready for war. When the possibilities in- volved in such a transformation are considered, it is little wonder that the Teutonic was a special object of interest in the great review. It has been decided by the British admiralty to build a new yacht for the queen, and the design has been submitted to and approved by her majesty. The new vessel, which will be built at the Pembroke dock yard, will, in general outline, resemble the great Atlantic liners. It will be 620 feet long, with only 50 feet beam, will be fitted with powerful engines, so as to have a great speed. While no expense will be spared. in order to make the vessel the finest of her class afloat in her decorations and fittings, she will closely resemble her majesty's present yacht, the Victoria and Albert. Screw Propeller Experiments, The inventor of the turbine engine for marine purposes failed in his first attempt, but to discover the cause he made some. very inter- esting experiments in propeller speed. He says that trials were made with screws of various patterns, but the results were unsatisfac- tory, and it was apparent that a great loss of power was taking place in the screw. To investigate the question thoroughly, a spring torsional dyna- mometer was constructed, and fitted between the engine and screw shaft, measuring the actual torque transmitted. The measurements conclusively proved that the cause of failure lay entirely in the screws, and, with the object of further investigating the character of this waste of power, a series of experiments were made with model two-bladed screws of 2-in diameter revolved in a bath of water heated to within a few degrees of the boiling point, and in order that the model screw should produce analogous results to the real screw, it was arranged that the temperature of the water and the head of the water above the propeller, as well as the speed of revolution, should be such as to closely resemble the actual conditions and forces at work in the real serew, the object in heating the water being to obtain an increased vapor pressure from the water, so as to permit a representation of the conditions with a more moderate and convenient speed of revolution than would otherwise have been necessary. -- The screw was illuminated by light from an are lamp reflected from a revolving mirror attached to the screw shaft, which fell on it at one point only of the revolution, and by this means the shape, form, and growth of the cavities could be clearly seen and traced as if sta- tionary. It appeared that a cavity or blister first formed a little behind the leading edge, and near the tip of the blade; then as the speed of revolution was increased, it enlarged in all directions until at a speed corresponding to that in the Turbinia's propeller, it had grown so as to cover a sector of the screw dise of 90 degrees. When the speed was still further increased, the screw, as a whole, revolved in a cylindrical cavity, from one end of which the blades scraped off layers of solid water, delivering them on to the other. In this extreme case nearly the whole energy of the screw was expended in maintaining this vacuous space. It also appeared that when the cavity had grown to be a little larger than the width of the blade, the leading edge acted like a wedge, the forward side of the edge giving negative thrust. From these experiments it would appear that in all screws, of whatever slip ratio, there will be a limiting speed of blade, depend- ing upon the slip ratio and the curvature of the back--in other words, on the slip ratio and thickness of blade; beyond this speed a great loss of power will occur; and that, should the speed of ships be' still further increased, the adoption of somewhat larger pitch ratios than those at present usual will be found desirable. It is not proposed here to trace further the losses of power by cavi- tation, but generally speaking, the effect is felt in the case of the real ship, not in the racing of the screw, but in loss of propulsion effect. In the model experiments, however, in hot water, the effect was both loss of propulsion effect and also racing, as would naturally be expected from the fact of greater vapour density of the water in the latter case rendering the cavities more stable. A series of model experiments on cavitation in cold water on the lines described would be extremely interesting, and probably instruc- tive, but would require more elaborate, powerful, and extremely high speed apparatus than was at our disposal. It would also seem that the limitation imposed on slip ratio tends in favour of larger pitch ratio for very fast vessels. The single compound turbine engine was now removed from the ~ boat and replaced by three separate compound turbines, directly coupled to three screw shafts, working in series on the steam, the tur- bines being the high pressure, intermediate, and low pressure, and designed for a complete expansion of the steam of 100-fold, each tur- bine exerting approximately one-third of the whole power developed, the three new screw shafts being of reduced scantling. By this change the power delivered to each screw shaft was re- duced to one-third, while the division of the engine into three was favorable to the compactness and efficient working of the turbines. The total weight of engines and the speed of revolutions remained the same as before. The effect on the screws was to reduce their - scantling, and to bring their conditions of working closer to those of ordinary practice. The thrust of the propellers is balanced by steam pressure in the motors.