THE MASTER WORKER 



of Parsons is not the only turbine wheel that has 

 proved commercially valuable. There is a turbine con- 

 sisting of a single ring of revolving blades, the invention 

 of Dr. Gustav De Laval, which has proved itself capable 

 of competing with the old type of engine. To make this 

 form of single turbine operate satisfactorily, it is neces- 

 sary to have steam under high pressure, and to generate 

 a very high speed of revolution. In practice, the De 

 Laval machines sometimes attain a speed of thirty 

 thousand revolutions per minute. This is a much 

 higher rate of speed than can advantageously be utilized 

 directly in ordinary machinery, and consequently the 

 shaft of this machine is geared to another shaft in such a 

 way as to cause the second shaft to revolve much more 

 slowly. 



