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26 MARINE REVIEW. [August 23, GAINS IN THE STEAM TURBINE. An'apparently important, and to the writer, at least, new, fact in the operation of the steam turbine is revealed by experimental investigations in progress for some time past in the laboratories of Sibley college, with both saturated and superheated steam. Contrary to the usual theory of that apparatus, it is found that a very substantial gain may be had by the use of superheat, not only in efficienéy, but also in capacity. The new steam turbine is not subject to that form of waste known as "initial" or "'cylinder" condensation which adheres to every piston- engine as a consequence of the large fluctuations of temperature which accompany the variations within the cylinder between boiler and con- denser pressures, and which, with the best of engines employing saturated steam, amount to 10 or 20 per cent. and to a multiple of such figures for small machines. The interior surfaces of the turbine, in steady working, remain at precisely the same temperatures and absolutely without those fluctuations which produce waste in the reciprocating and in the other forms of rotary engine. As it is to reduce this particular waste that super- heating is employed, ordinarily, there would not 'be expected to be found any other gain by its use in the steam turbine than that increase of ther- modynamic efficiency which is due to the widened range of temperature, in this case amounting to about one-tenth of one per cent. per degree of superheat. Investigations by Messrs. Schieren and Thomas, above alluded to, show, on the contrary, a gain of about one per cent. for each one and two-thirds degrees centigrade, three Fahrenheit degrees, of superheat and the remarkable and unexpected result of an increase in the capacity of the machine of about 100 per cent. by the use of but twenty degrees centigrade, thirty-seven degrees Fahrenheit, superheat. The "wwater-rate"' of the turbine, a La Val machine of 10 H. P. as rated, de- creased from about 21.7 kilogrammes, 48 lbs., with pressure rising from 21.7 kilogrammes, 44 Ibs., to 1.99 kilogrammes, 44 lbs., with pressure rising from three atmospheres to eight, with a two-thirds vacuum, and with saturated steam; while the figures fell off about 12 per cent. with super- heating, rising to a very moderate maximum as above. Deduced to thermal units per horsepower per hour, the same effect appears in a very similar proportion. The causes of the gain in thermodynamic efficiency and of capacity are presumably identical--the extinction of the friction wastes due to:the retardation of the current of fluid traversing the passages of the turbine by concurrent resistances coming of the weighting of the current of steam with drops and mist and the adherence of moisture in mist, drops and even streams, very probably, to the walls of the steam passages of the turbine. The phenomenon will, however, be the subject of extended investigation in the course of the work in research constantly in progress and a way will be found of precisely identifying the cause and determining the laws governing its action in the production of these variations of efficiency and capacity. That this apparently obvious expla- nation is the correct one and, certainly, that the gain is not due to any such action as produces the remarkable beneficial effects observed in the reciprocating engine, is tolerably well indicated by the fact that the gain, in this case, by superheating, is substantially proportional, so far as here carried, to the amount of superheat and the graphic log shows a straight line of decreasing consumption of steam.--Prof. R. H. Thurston, in Science. TWENTY YEARS' PROGRESS IN MACHINERY, Dealing with the subject "Twenty Years' Progress in Cargo Boat Machinery," Mr. J. F. Walliker, member of the British Institute of Ma- rine Engineers, said in a paper read recently before that society that in his opinion the most advanced type of multiple-expansion engine was that with five cranks designed and introduced by the late Mr. Mudd. Engines of this type were said to be propelling a vessel of 5,800 tons at an average speed of 9 knots on 13% tons of coal, or at the rate of 1 Ib. per I. H. P. per hour. In 1872 the average coal consumption was 2.11 lb. per I. H. P., and in 1881, 1.828 lb., while to-day the ordinary cargo boats average 1.5 lb. per I. H. P. for all purposes. The author con- siders the principal drawbacks of the engines of the present day are the screw shaft and the steam pipes. With regard to the former, two things have always appeared inexplicable, first that the shaft should be the only piece of machinery in the ship supposed to be capable of running with water alone, and the other that when one form of shaft has failed an alteration in form and design is not adopted, but the old error is repeated. As regards steam pipes he is disappointed at the slow progress made in the use of the expansion gland. Being practically a universal joint and not liable to give trouble in any way whatever, it seems to.suggest that it will come into general use, after the trouble experienced by pipes breaking at the flange through stress has been thoroughly appreciated. He be- lieves the day will come when the custom of depending on beds alone for the necessary elasticity and expansion will be a thing of the past. Owing to the enhanced importance of the machinery since the practical abolition of masts, he predicts that there will be a time when the master will act as chief engineer, and as a step in this direction he suggests that engineers should be encouraged to pass an examination and receive a certificate for proficiency in navigation, in the same way that deck officers are at the present time enabled to pass one in steam. In con- clusion the author summarized the progress of the last twenty years as consisting of: Iron replaced by steel in boiler manufacture; three, four, and five-crank engines adopted; working pressure increased; coal con- sumption reduced; average size increased; and corrosion in boilers prac- tically prevented. STEAMBOAT ON LAKE TITICACA, An interesting engineering feat which has recently been accomplished is the placing of a steamboat of 550 tons on Lake Titicaca, between Bolivia and Peru, a sheet of water 120 miles lone. 325 miles from a sea- port, and nearly 13,000 ft. above the sea level. This vessel was built at Leven ship yard, Dumbarton, Scotland, temporarily put together, and then transported in sections to Mollendo, whence it was carried in twenty-two cars up the railroad which skirts the steep sides of the Andes to the lake side. There it was once more put together and the boilers and engines installed. The Coya (such is the vessel's name) is 170 ft. long, 26 ft. beam and has accommodations for forty-five first-class and forty second-class passengers. The distance traversed by this steamer is 100 miles, the journey occupying ten hours. The vessel serves as a means of communication between the republics of Bolivia and Peru. AMERICAN BRIDGE CO. 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