The first steam-turbines were used to drive dynamos. In 1884 Mr. Parsons made a turbine in which fifteen wheels of increasing size moved at the astonishing rate of 300 revolutions per second, and developed 10 horse-power. In 1888 followed a 120 horse-power turbine, and in 1892 one of 2000 horse-power, provided with a condenser to produce suction. So successful were these steam fans for electrical work, pumping water and ventilating mines, that Mr. Parsons determined to test them as a means of propelling ships. A small vessel 100 feet long and 9 feet in beam was fitted with three turbines--high, medium, and low pressure, of a total 2000 horse-power--a proportion of motive force to tonnage hitherto not approached. Yet when tried over the test course the _Turbinia_, as the boat was fitly named, ran in a most disappointing fashion. The screws revolved _too fast_, producing what is known as _cavitation_, or the scooping out of the water by the screws, so that they moved in a partial vacuum and utilised only a fraction of their force, from lack of anything to “bite” on. This defect was remedied by employing screws of coarser pitch and larger blade area, three of which were attached to each of the three propeller shafts. On a second trial the _Turbinia_ attained 32-3/4 knots over the “measured mile,” and later the astonishing speed of forty miles an hour, or double that of the fast Channel packets. At the Spithead Review in 1897 one of the most interesting sights was the little nimble _Turbinia_ rushing up and down the rows of majestic warships at the rate of an express train. [Illustration: _H.M.S. Torpedo Destroyer “Viper.” This vessel was the fastest afloat, attaining the enormous speed of 41 miles an hour. The screws were worked by turbines, giving 11,000 horse-power. She was wrecked on Alderney during the Naval Manoeuvres of 1901._] After this success Mr. Parsons erected works at Wallsend-on-Tyne for the special manufacture of turbines. The Admiralty soon placed with him an order for a torpedo-destroyer--the _Viper_--of 350 tons; which on its trial trip exceeded forty-one miles an hour at an estimated horse-power (11,000) equalling that of our largest battleships. A sister vessel, the _Cobra_, of like size, proved as speedy. Misfortune, however, overtook both destroyers. The _Viper_ was wrecked August 3, 1901, on the coast of Alderney during the autumn naval manoeuvres, and the _Cobra_ foundered in a severe storm on September 12 of the same year in the North Sea. This double disaster casts no reflections on the turbine engines; being attributed to fog in the one case and to structural weakness in the other. The Admiralty has since ordered another turbine destroyer, and before many years are past we shall probably see all the great naval powers providing themselves with like craft to act as the “eyes of the fleet,” and travel at even higher speeds than those of the _Viper_ and _Cobra_.