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TAE MARINE REVIEW NAVAL ARCHITECTS AND MARINE ENGINEERS. THE DISCUSSION UPON THE TURBINE PAPERS BY CURTIS AND SPEAKMAN WAS OF THE MOST ANI- ? MATED AND VALUABLE CHARACTER. In relating the financial condition of the Society of Naval Architects and Marine Engineers in thesissue of November 23, it should have been clearly stated that while the total receipts for the year were $10,620,81 and expenses $9,611, leaving a balance on hand of $1,009.49 that $1,500 of the receipts of the year were invested in certificates of deposit drawing interest, so that the real balance for the year was $2,509.49. This makes the financial status of the society eminently satisfactory. Although eight deaths and thirty-one resignations occurred during the year, there were elected forty-three members, so that there was an actual gain of four in the total membership. Probably the most important papers read at the ses- sions were the two turbine papers--one "Marine Turbine Propulsion," by Mr. Charles C. Curtis, and the other on "Marine Steam Turbine Development. and Design," by E. M. Speakman, of, England. Mr, John H. Mac- alpine, who with Admiral Melville went abroad at the instigation of George Westinghouse, related the results of his inquiries in the most guarded language, but the inference was clear that he did not regard the turbine as a success. Mr. Speakman's paper, which was very ex- haustive, will be given in full later. Before reading his paper, Mr. Curtis said: "T am afraid my little paper will sound very insignifi- cant and uninteresting after the very technical and elaborate papers, some of which have been read _ this morning, and one of which, on this interesting subject is to follow mine; but I think it might be interesting to state some of the results that we have obtained and what is being done in the application of this particular type of turbine to marine work." Mr. Curtis' paper was as follows: The first vessel to be propelled by steam turbines of this type, and the first vessel of any kind to be fitted with twin shafts and screws, and twin turbines inde- pendently controllable and reversible, was the yacht _ Revolution, built in 1902. This yacht had a length of 140 feet on the water 'line, beam of about 17 feet, a draught of 7 ft. and a displacement of about 200 tons, and was provided with two independent turbines of about 1,200 H. P. each, turning outward and designed to run between - 650 and 750 revolutions under full speed conditions. The turbine casing, including the reversing mechanism, was only 5 ft. 10 in. in diameter and about 4 ft. long. The turbines were not designed to show any remarkable eco- 'nomy, but were expected to consume about the same. amount of steam as an ordinary triple expansion engine under the usual conditions of service. This yacht was put into commission in the spring of 1902 and was kept in commission and used for exhibition purposes continually, with the exception of two months during one winter, for a period of a year and a half. : The practical operation of the turbines was in every respect most satisfactory and convincing, neither one ever having required any repairs of any kind, and the steam consumption was shown by torsion shaft test to be substantially equivalent to that of the ordinary triple expansion engine under average working conditions. The boat, however, failed to develop the speed antici- pated, and it was a long time before we could find out why this was so. The impression seems to have got abroad among marine engineers that the failure of this boat to show a speed consistent with the high power provided was in the main due to a failure of the turbines to develop the necessary H. P. Such was not the fact. One of the turbines when driving the sczew in the ordinary way, was subjected to a very. careful torsion shaft test by Prof. James E. Denton, who, with Prof. Webb, devised and worked out an ingenious and accurate method of measuring the angle of twist of a specially calibrated length of torsion shaft introduced into the line shaft for this purpose. The tests showed that the turbines developed the full power expected, and that the steam con- sumption was about 1714 pounds per I. H. P.. The re- sults are given in the following table:-- POWER AND ECONOMY OF ONE TURBINE. Brake H.P., I.H.P.of Dry steam per Number of Revolu- or H.P.deliv- equivalent I. H. P. of equi- steam pas- tions per ered to pro- pistonen- valent piston sagesinuse. minute. feller. , gine. engine. I 2 3 4 5 4 748.0 1,096.0 1,267.0 17.46 4 748.0 1,096.0 1,267.0 17.46 3 672.8 761.6 808.7 18.14 2 506.6 467.1 572.0 19.12 I 452.5 192.3 269.5 21.34 1 throttled, 265.3 05.7 146.2 24.67 The failure to get the expected speed, viz: 21 to 21% knots under conditions where the boat actually showed only about 18 knots, furnishes another illustration of how easy it is to "fall down" in an engineering matter of this kind, even when the best knowledge and talent are availed of. In order to insure success we not only had the vessel designed by a well kown firm of yacht designers and build- ers who had previously built a yacht which was and still is the fastest yacht in this country, but we had the yacht's model tested in the government testing tank in Washing- ton, and the screws were designed by a very distinguished authority in this country. Several sets of screws were built for the boat, the last set having a diameter of 4 ft. and a pitch of 4 ft. and having thin blades of well known form. From what is now known of the action of pro- pellers of this character and from the fact that the tur- bines did develop the power expected, we have been led to conclude that the trouble with the Revolution was in her model, which, in the afterbody is very bad, her floor not being drawn out aft far enough. This view is con- firmed by the best marine architects whom we have con- sulted about the matter and who have observed the wave action of the boat, which is very excessive, even at a speed of only 18 knots. The reversing and manoeuvering capacity of the Revolu- tion was even better than anticipated, and was very satis- factory. In a manoeuvering test made by a Board of the Navy Department it was found that when going ahead at full speed (about 18 knots) the boat was brought to a standstill in the water in.32 seconds after the engine room telegraphs were thrown over.. The boat was used extensively about New York Harbor for a year and a half, and her reversing power was called into play to the utmost very frequently but it never failed to respond with the neces- sary power, and during the whole period of her use as a "demonstration" no trouble of any kind whatever was had with either of the two turbines... Some time ago the Fore River Shipbuilding Company of Quincy, Massachusetts, at the instance of its very, able and progressive president, Admiral Bowles, and after an investigation into the comparative merits of the two. types of steam turbines available for the purpose, entered into