The De Laval turbine, as shown in Fig. 88, is of very simple construction, consisting only of a steel wheel with a series of buckets at its periphery enclosed by a circular rim, and a series of steam nozzles on the side with diverging jet orifices directing steam jets against the buckets. A speed of 30,000 revolutions a minute may be attained by this construction. In Fig. 89 is shown a 300 horse-power steam turbine of the De Laval type applied to a dynamo; to which this type of engine is peculiarly adapted. The dynamo is seen on the extreme right, the steam turbine on the extreme left, and the drum-shaped casing between contains cog-gearing by which the high revolution of the turbine wheel is reduced to a proper working speed for the dynamo. Within the last few years application of the Parsons steam turbine has been made to marine propulsion with very remarkable results as to speed. The small steam craft, “The Turbinia,” built in 1897, and supplied with three of Parsons’ compound steam turbines, developed a speed of 32¾ knots, and more recently the torpedo boat “Viper” has with steam turbines attained the remarkable speed of 37.1 knots, or over 40 statute miles an hour. About 2,000 United States patents have been granted on various forms of rotary engines. In the transportation building of the World’s Fair at Chicago in 1893 one of the most conspicuous objects of attention was the model of the great Bethlehem Iron Co.’s steam hammer, standing with its feet apart like some great “Colossus of Rhodes” and towering 91 feet high among the models of the great ocean steamers and battleships which are so largely dependent upon the work of this Titanic machine. Its hammer head, in the working-machine, weighs 125 tons, and many of the seventeen inch thick armor plates for our battleships have been forged by its tremendous blows.