Engineering Wonders of the World
Volume I

ENGINEERING WONDERS OF THE WORLD. 30 Fig. 1.—SECTIONAL DIAGRAM SHOWING PROPELLING MACHINERY OF THE “ CHARLOTTE DÜNDAS ” (1801). ENGINES BY WILLIAM SYMINGTON. CRischgitz Collection.) associated with the higher pressure. Thus, in the earliest marine engines, with their low working pressure, a single cylinder sufficed for the small range of steam expansion ; so, after passing through this cylinder, the steam was taken direct to the condenser. With higher working pressures, however, the increased range of expansion led to the use of two cylinders in the compound engines fitted in the larger vessels built about thirty years ago. In the compound engine, the steam, after performing its work in the first, or high-pressure, cylinder, passes into a second and larger cylinder, known as the low-pressure, before exhausting into the condenser. Some twenty years ago the work- ing pressure had so far increased that three stages in the steam expansion became desir- able ; hence the triple-expansion engine, with three cylinders of increasing size, known re- spectively as the high-pressure, intermediate, and low-pressure, was introduced. Still more recently, the quadruple-expansion engine, an illustration of which we give later, has been adopted largely for high-powered steamships. The compound engine usually takes steam from the boiler at about 80 lbs. pressure per Pig. 2.—THE “ TURBINIA,” THE FIRST TURBINE VESSEL, BESIDE THE GIGANTIC TURBINE-DRIVEN CUNARDER “ MAURETANIA.”