Turbine waterwheels. Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for invention of the steam turbine is given both to Anglo-Irish engineer Sir Charles Parsons (1854–1931) for invention of the reaction turbine, and to Swedish engineer Gustaf de Laval (1845–1913) for invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery. The word "turbine" was coined in 1822 by the French mining engineer Claude Burdin from the
Pennsylvania-class steamship Pennsylvania-class steamship The "Pennsylvania" class steamships—"Pennsylvania", "Ohio", "Indiana" and "Illinois"—were a class of four cargo-passenger liners built by the Philadelphian shipbuilder William Cramp & Sons in 1872–73. Intended for the newly established American Line, the four ships were at the time the largest iron ships yet built in the United States, and were launched with considerable fanfare. Upon entering service in 1874, they also became the first American-built steamships to challenge British dominance of the transatlantic trade since the American Civil War. Although soon outclassed by newer and larger vessels, all four of the "Pennsylvania" class steamships were to enjoy