All About Engines

i64 All About Engines mixed with the steam. The condensed steam, there- fore, is practically free from oil and can be used to feed the boilers — a great advantage where pure water for boiler feeding is not easily obtained. These turbines are made in sizes from 20 to over 12,000 horse-power, and run at speeds from 750 to 4,000 revolutions per minute. The Reaction Turbine The year before Dr. de Laval patented his impulse turbine the Hon. (now Sir) Charles A. Parsons in- vented one of a different type. Sir Charles Parsons is the son of the Earl of Rosse, who constructed the enormous reflecting telescope about which every- body who has read anything on astronomy must have heard. He was, therefore, brought up in an atmosphere of mechanical ingenuity, and after be- coming Senior Wrangler at Cambridge he devoted himself to engineering, and soon proved his power and originality by his new invention. Just as the Swedish engineer had adopted the same principle as Branca, with that special modifi- cation of the form of the jet which is based on scien- tific knowledge of the properties of steam which has been discovered long since Branca died, so Sir Charles Parsons adopted the principle employed by Hero, and brought to bear upon the problem the mathematical and scientific knowledge built up by 2,000 years of human genius and human in- dustry. What the impulse principle is, and how it is applied has already been described, and we