Page:The Steam Turbine.djvu/42

 replaced by three turbines in series (on the steam) on different shafts (page 26), and it is adopted in all the largest liners and almost all large war vessels. In marine work this division of the turbine has the additional advantage that owing to the power being subdivided over three shafts, smaller screws are admissible, and the speed of revolution may be increased in the case of three turbines in series in the ratio of 1 to &radic;3. Generally the turbines are placed two in series, as in cross-channel boats, the "Mauretania" and "Lusitania," torpedo craft, battleships, and cruisers (page 27), or sometimes three in series (page 29) as in the liner "La France" and the latest and largest Cunard liner now building. Four turbines in series have been proposed, but have not as yet been constructed.

A war vessel in commission is working at reduced power for most of the time, and on long voyages economy of fuel is of great importance. To attain this end, additional turbines are fitted in front of the main full power turbines. They are of small size, and