STEAM TURBINES, MARINE. The first vessel to be fitted with turbines was the "Turbinia." In 1897 she was equipped with turbines of the Parsons type, three engines being used, high pressure, intermediate and low. Each shaft was fitted with three propellers. She attained the remarkable speed of 341/2 knots per hour, and the results ob tained in her trials were considered so successful that the adoption of turbines in other vessels very quickly followed. In 1900 the British destroyer "Viper," turbine driven, made 361/2 knots per hour. Passenger vessels, being built for convenience rather than speed, naturally did not make such a remarkable show ing, but nevertheless, greater speeds were attained than had been found pos sible with the ordinary reciprocating engine. The first turbine driven pas senger vessel was the "King Edward," which reached 20% knots in 1901. The first transatlantic liners fitted with tur bines were the "Victorian" and "Vir ginian," whose maximum speed reached only 17 knots per hour. In 1907, how ever, the Cunard line built the "Lusi tania" and the "Mauretania." These were quadruple screw turbines of 67, 000 indicated horse power, equipped with two high pressure, two low pres sure, and two reversing turbines. These vessels were capable of maintaining an average speed of 26 knots per hour. In 1906, the British battleship "Dread nought" was built and fitted with tur bines, this being the first battleship to be so equipped. During her trials a speed of 21.25 knots was attained. Of recent years the number of vessels which have been equipped with turbines of im proved pattern has been very great, the advantage of the turbine for marine work being now generally recognized.
The superiority of turbines over recip rocating engines is not solely due to the extra speed which can be attained. A turbine is lighter, of simpler construc tion, and more compact than a recipro cating engine. There is also much less vibration. At high speed there is a marked economy of fuel, but at low or moderate speed, the turbine consumes more coal than the reciprocating engine.
For general purposes, the turbine is proving more satisfactory than the re ciprocating engine in nearly all cases where high speed is required. It is, however, of little use for low speeds, or in those cases where a heavy resistance has to be overcome when starting from rest. It is peculiarly adapted for driv ing dynamos. Its simpler construction is a strong point in its favor, its moving parts being much fewer than in the re ciprocating engine. Moreover, the fact that the steam acts directly on the mov ing shaft without the intervention of pistons, connecting rods, etc., leads to greater efficiency. The comparatively late date at which it was developed for practical purposes is explained by the need for special steels and other alloys possessing the unusual strength and other properties required in engines of this type. In this connection, Kempe's "Engineer's Year Book" states, "A very important fact in the evolution of the steam turbine has been the introduction of the high grade steels now available, which alone have made the highest peri pheral speeds now to be met with pos sible, and further developments may be expected to follow any reduction in the cost of finest steels."