At the grand naval review held in 1897 in honour of Queen Victoria's diamond jubilee, one of the most noteworthy sights was the little _Turbinia_ of 44-1/2 tons burthen, which darted about among the floating forts at a speed much surpassing that of the fastest "destroyer." Inside the nimble little craft were engines developing 2,000 horse power, without any of the clank and vibration which usually reigns in the engine-room of a high-speed vessel. The _Turbinia_ was the first turbine-driven boat, and as such, even apart from her extraordinary pace, she attracted great attention. Since 1897 the Parsons turbine has been installed on many ships, including several men-of-war, and it seems probable that the time is not far distant when reciprocating engines will be abandoned on all high-speed craft. DESCRIPTION OF THE PARSONS TURBINE. [Illustration: FIG. 37.--Section of a Parsons turbine.] The essential parts of a Parsons turbine are:--(1) The shaft, on which is mounted (2) the drum; (3) the cylindrical casing inside which the drum revolves; (4) the vanes on the drum and casing; (5) the balance pistons. Fig. 37 shows a diagrammatic turbine in section. The drum, it will be noticed, increases its diameter in three stages, D^1, D^2, D^3, towards the right. From end to end it is studded with little vanes, M M, set in parallel rings small distances apart. Each vane has a curved section (see Fig. 38), the hollow side facing towards the left. The vanes stick out from the drum like short spokes, and their outer ends almost touch the casing. To the latter are attached equally-spaced rings of fixed vanes, F F, pointing inwards towards the drum, and occupying the intervals between the rings of moving vanes. Their concave sides also face towards the left, but, as seen in Fig. 38, their line of curve lies the reverse way to that of M M. Steam enters the casing at A, and at once rushes through the vanes towards the outlet at B. It meets the first row of fixed vanes, and has its path so deflected that it strikes the ring of moving (or drum) vanes at the most effective angle, and pushes them round. It then has its direction changed by the ring of F F, so that it may treat the next row of M M in a similar fashion. [Illustration: FIG. 38.--Blades or vanes of a Parsons turbine.] [Illustration: One of the low-pressure turbines of the _Carmania_, in casing. Its size will be inferred from comparison with the man standing near the end of the casing.] THE EXPANSIVE ACTION OF STEAM IN A TURBINE.