334 The Hon. G. A. Parsons on The Steam TurUm [May 4, 



reciprocating engine cannot do, and the combination is therefore a 

 good one. For manoeuvring or stopping the vessel, either the engine 

 or the turbines, or both, may be used, and there seems to be no doubt 

 that this arrangement will come into vogue for the slower class of 

 vessels of larger size. 



Turbines have been applied to other uses within the last ten years. 

 The most important of these are for the working of rotary blowers, 

 air-compressors, and water-pumps. 



The photograph. Fig. 8, shows a cross-section through a turbo- 

 blowing engine, capable of compressing 21,000 cubic feet of free air 

 per minute to a pressure of 17 lbs. per square inch, which represents 

 about 1000 horse-jwwer in the air, reckoned in adiabatic compression. 

 In general construction the turbine air-blower portion is similar to a 

 steam turbine. The blades or vanes which propel the air are plano- 

 convex in section, and set in rows at an angle similar to that of the 

 blades of a ship's propeller. Between the rows of moving blades are 

 rows of guide-blades inwardly projecting from the case. These latter 

 are also of plano-convex section, and are set with their plane surfaces 

 parallel to the axis ; and their purpose is to assist the flow, and to stop 

 the rotation of the air after being acted on by the moving blades. 

 Each row of moving and fixed blades adds a little to the pressure, and 

 compresses the air gradually along the annular space between the 

 drum and the case. Balance pistons or dummies are provided for 

 balancing the end-thrust of the air, as in the steam turbine. The 

 speed of rotation is 3600 revolutions per minute, and the tip velocity 

 of the air blades about 400 feet per second. 



[C. A. P.] 



