A casing can be placed around the turbine to control the movement of the fluid. Credit for the invention of the steam turbine is given both to Anglo-Irish engineer Sir Charles Parsons (1854 - 1931) for invention of the reaction turbine(turbines that utilize water pressure and water speed to rotate), and to the Swedish engineer Gustaf de Laval (1845-1913) for invention of the impulse turbine. Modern steam turbines normally utilize both the reaction and impulse turbine in one system.