1011] Recent Advances in Turbines. 91 



AVEEKLY EVENING MEETING, 



Friday, March 10, 1911. 



Silt William Crookes, O.M. LL.I). D.Sc. F.R.S., Honorary 

 Secretary and Vice-President, in the Chair. 



The Hon. Sir Charles A. Parsons, K.C.B. J.P. 

 M.A. Sc.l). LL.D. F.R.S. 



Recent Advances in Turbines. 



On two previous occasions I have addressed this Institution on the 

 steam turbine. At the time of the first lecture, in 11)00, the turbine 

 may be described as having been in the " advanced experimental stage." 

 Six years later it was meeting with " general acceptance " in certain 

 fields. To-night I propose to review its progress from IDOG to the 

 present time ; l)ut before doing so I shall, with the view of leading 

 up to the subject, and at the risk of some repetition, briefly explain 

 the chief features of interest, and recapitulate some of the earlier 

 steps in its introduction. 



The first turbine of which there is any record was made by Hero 

 of Alexandria 2000 years ago, and it is probably obvious to most 

 persons that some power can be obtained from a jet of steam either 

 by the reaction of the jet itself, like a rocket, or by its impact on 

 some kind of paddle-wheel. It is, however, not so obvious that an 

 economical engine could be made on this principle. In the year 1888 

 Dr. de Laval, of Stockholm, undertook the problem with a considerable 

 measure of success. He caused the steam to issue from a trumpet- 

 shaped jet, so that the energy of expansion might be utilised in giving 

 extra velocity to the steam. Recent experiments have shown that by 

 such a device nearly the whole of the available potential energy in the 

 steam is converted into kinetic energy of velocity in a straight line, 

 the velocity attained into a vacuum being about 43,000 feet per second. 

 Dr. de Laval caused the steam to impinge on a paddle-wheel made 

 of the strongest steel, which was allowed to revolve at the highest 

 speed consistent with safety, for the centrifugal forces are enormous. 

 Unfortunately, materials are not strong enough for the purpose (in 

 the large sizes the speed is nearly half that of a rifle bullet), and the 

 permissible speed of the wheel can only reach to two-thirds of that 

 necessary for good economy, as we shall presently explain. 



Dr. de Laval also introduced spiral helical gearing for reducing the 

 enormous speed of his wheel to the ordinary speeds of things to be 



