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"TAE Marine. Review = 27 for the British admiralty. These two vessels were fitted with additional engines for obtaining economical results when cruising at low speeds. The Velox was fitted with two small auxiliary reciprocating engines, whereas the Eden was fitted with two cruising turbines. When cruis- ing at low speeds, the steam from the boiler passes through the two cruising engines in the case of the Velox, and the two turbines in series in the case of the Eden, and thence to the main turbines and condensers. An efficient expansion of the steam is thus secured from the boiler to the condenser pressure. The latest vessel to be fitted with turbines, for the British admiralty was H. M. third- class cruiser Amethyst. This vessel is also fitted with cruising... turbines, and. the results of the. trials, give. the comparative performances of the tur- bine . machinery. as compared with sister vessels ordered -at the same time as. the Amethyst, and of the same dimensions and lines, but fitted with recipro- cating engines. The trials of these ships unmistakably demonstrated the economy of the Parsons' marine tur- bine as fitted in this class of vessel, and more especially at the higher power. THE GREAT CUNARDERS. One of the greatest steps in the application of the tur- bine to marine propulsion was, undoubtedly, when the Cunard Steamship Company, after thorough investigation into the technical details and capabilities of the turbine by a. committee of leading . engineering ex- perts, decided to adopt turbine machinery for their twe new express liners, designed to be the largest, fastest, and most powerful vessels afloat. The author well re- members when Mr. Parsons, in one of the earlier papers, delivered before one of. the leading technical associations, previous to the King Edward being tried, suggested that the proposal to fit Atlantic liners with turbines of 20,000 to 30,000 I. H. P. presented no great difficulties. The major- ity of engineers, who were imbued with the idea that what Mr. Parsons was attempting was impossible, were rather startled, and yet, within the period of four years since the first mercantile vessel was built, the turbines for the express Cunarders are under construction, each of more than double the horsepower mentioned by Mr. Par- sons in the paper referred to. At the same time as it was arranged to fit the two express Cunarders with Par- sons' turbines it was decided to fit one of the two inter- mediate Cunard liners, viz., the Carmania, then on order with Messrs. John Brown and Co., Clydebank, with tur- bines, thus forming a direct comparison with the sister vessel, the Caronia, fitted with reciprocating engines, and the results of the trials, which have appeared in Engin- eering and other leading papers, showed that the Car- mania obtained a mean speed of 20.2 knots per hour, which was estimated to be about one knot faster than the Caro- nia, under similar conditions, and on service, the coal con- sumption on her first voyage has been reported to com- pare favorably with the very satisfactory performance of the Caronia in this respect. THE PROPELLER PROBLEM. It may be of interest, at this stage, to mention a few points incidental to the application of the turbine system to different classes of vessels. It is desirable, for obvious reasons, that a turbine for a given efficiency should be de- signed to run at as high a rate of revolutions as possible, consistent with propeller efficiency. The speed of turbines for land purposes is considerably higher than is permis- sible for turbines for. marine purposes where the speed of rotation is limited by considerations of propeller effi- ciency. As already referred to, the great difficulty which Mr. Parsons had to contend with arose in connection with the number of propellers to adopt to obtain the best com- promise of turbine and propeller efficiency. In the Tur- binia, and in several of the earlier vessels, a considerable number of experiments were carried out with various de- signs of propellers. With the original engine that was tried in the Turbinia, nine propellers in all were tested, with the same unsatisfactory result. After the original turbine was removed and replaced by the existing three _ turbines, further propeller experiments were carried out. The first set tried consisted of three propellers on each shaft--nine in all--of 18 inches diameter and 18 inches pitch, which gave favorable results. Subsequently other sets were tried, and the set eventually adopted comprised three propellers on each shaft--nine in all--of 18 inches diameter and 24 inches pitch, so that dividing the power over the three shafts, a considerable increase in efficiency was obtained, and a speed of 32 knots was reached. In _ May, of 1902, further experiments were made with single propellers on each shaft. Progressive runs were first made with the nine propellers, when it was found that the speed relative to water consumption followed exactly the same curve as that' obtained by Professor Ewing previously. The first set of single propellers tried were 28 inches dia- meter and 28 inches pitch, and the second set were of the .same diameter, but with a pitch ratio of .8. The loss of efficiency which has been observed in some of the earlier vessels which were fitted with multiple propellers appears to have been due partly to the interference from the for- ward screws and partly to cavitation. There is no doubt that for certain classes of vessels the turbine has a distinct advantage over the reciprocating engine, and the larger the power of the machinery and the higher the speed of the vessel, the more favorable is the comparison with tur- bines as regards economy. There is, however, at the pres- ént. time, a lower limit of speed of vessel below which this advantage gradually disappears, and this speed would appear to be, generally speaking, about 15 knots, with a corresponding horsepower of about 1,600. With higher powers (say) 5,000 to 6,000, then probably a lower speed of (say) 14 knots might compare favorably with reciprocating engines. For lower speeds of vessel, to ob- tain reasonable propeller efficiency, a certain diameter of propeller is necessary, and the revolutions to corres- pond are moderately low, and as it is necessary to obtain a certain surface speed of turbine, as well as a certain number of rows of turbine blades, to obtain reasonable economy, the size of the turbine becomes great in pro- portion to the power, the efficiency being somewhat im- paired thereby; moreover, the weight and cost is increased as compared with turbine machinery of similar powers for 'higher speeds of vessel. PARSONS' TURBINES' PECULARITIES. In regard to the arrangement of turbines, this partly depends upon the condition of service, and the various classes of vessels require, more or less,-to be taken upon their own merits.. The arrangement which has been al- most universally adopted in the mercantile marine is that of dividing the power equally over three shafts, viz. a high pressure on the center shaft, exhausting into two low-pressure turbines one on each side of the vessel. In such a case the high-pressure turbine is made suitable for an expansion ratio of about five, and the low pressure for 2s. No doubt the members of this institution are more or less conversant with the principle of the Parsons turbine. Each turbine consists of a number of rings of blades or vanes mounted on a drum or rotor. This rotor is en- closed within a cylindrical case, upon which rings of blades are also fitted. The rings of blades are alternately fixed and moving, that is to say, the blades in the cylinder