SECTION MECHANICS (including Pure and Applied 

 Mathematics and Mechanical Drawing). 



Thursday, May 2$t/i, 1876. 



Dr. SIEMENS, President, in the Chair. 



F. J. BRAMWELL, M. Inst. C.E., F.R.S. : The subject on which I 

 have now the honour to address you, the subject which is to occupy our 

 attention to-day, is that of " Prime- Movers," that is to say, we are about 

 to consider that class of machines which, to use the words of Trc dgold, 

 41 enable the engineer to direct the great sources of power in Nature for 

 the use and convenience of man." 



Although machines of this kind are in truth mere converters or 

 adapters of extraneous forces into useful and manageable forms, and 

 have not any source of life, power, or motion in themselves, never- 

 theless they impress us with the notion of vitality ; and it is difficult 

 to regard the revolving shaft of a water-wheel or turbine set in motion 

 "by some hidden stream, or to gaze upon the steam-engine actuated by 

 an unseen vapour, without, as I have said, the idea being raised in 

 our minds that the machines on which we are looking are really en- 

 dowed with some kind of life; and thereupon not inaptly, although 

 not quite accurately we speak of them as Prime-Movers. 



The invention of Prime-Movers marks a very great step in the pro- 

 gress of mechanical science in the world, as it commences an era dis- 

 tinct from that in which mere machines, to be acted on by human or 

 animal muscular force, were alone in existence. Machines such as 

 these, highly useful as they may be, are, after all, only tools or imple- 

 ments more or less ingenious, and more or less complex. 



Mankind could not have been very long upon the earth before they 

 must have found the need and must have discovered the utility of some 



