98 Recent Advances in TtirMnes. [March 10, 



turbine. Their use will increase the radius of action of the vessels at 

 cruising speed to a very considerable extent over that of any similar 

 destroyer without gearing. Similar gearing is proposed for warships, 

 with similar prospective advantages. 



Gearing may also find a place in cross-Channel boats and liners 

 for the high-pressure portion of their turbines, but the greatest 

 material gain will be in extending the use of turbines to vessels of 

 slow speed. 



Gearing enables very high coejficients to be used in marine work 

 at full speed, and good coefficients at all speeds without much increase 

 in weight, and under such conditions a geared high-speed reaction 

 turbine is much more efficient at the high-pressure end than the 

 multiple impulse wheel or wheels we have considered, and will pro- 

 bably dispense with their use generally. Gearing in marine and land 

 work promises to give to the turbine a level consumption curve like 

 that of the gas and oil engine. Half a century ago nearly all screw 

 vessels had mechanical gearing, one element being composed of wooden 

 teeth, for gearing up the speed of the engine. Subsequently the 

 speed of engines was increased, and gearing abandoned. Now a very 

 slow-speed turbine is an impossil)ility, and accurately cut steel gearing 

 seems to be a permanent and satisfactory solution. 



Low-pressure turbines worked by the exhaust steam from other 

 engines are coming into general use on land under the name of " The 

 utilisation of exhaust steam," for they utilise what was formerly a 

 waste product, the exhaust steam from non-condensing engines. 



They are generally employed in the generation of electricity or in 

 the working of blast-furnace blowers and centrifugal pumps and gas 

 forcers, but recently an exhaust turbine of 750 horse-power has been 

 applied to driving an iron-plate mill in Scotland. The turbine re- 

 volves at 2000 revolutions per minute, and by a double reduction of 

 helical gears drives the mill at 70 revolutions. A fly wheel of 100 

 tons weight revolving at the same speed as the rolls equalises the 

 speed. During each rolling the turbine and flywheel collectively ex- 

 ert 4000 horse-power, the maximum deceleration at the end of each 

 roll being only 7 per cent. 



So satisfactory has gearing proved up to the present on a small 

 and also comparatively large scale, that it seems probable that by its 

 use turbines will be more widely adopted in the future for power pur- 

 poses generally. 



There are at the present time just above 6,000,000 horse-power of 

 marine turbines completed and building, and also an equal horse- 

 power of land turbines of the compound reaction type. 



