WILLIAM SIEMENS, F.R.S. 289 



poses where such degrees of heat are required that the electric arc 

 can be advantageously employed, and will enable us to accomplish 

 chemical ell'rrts which have hitherto been beyond the reach of 

 science. 



My chief object in dwelling, perhaps unduly, upon these 

 practical questions is to present to your minds in a concrete form 

 the hopelessness of looking upon any of the practical processes of 

 the present day as permanent, to be acquired in youth and to be 

 the staple occupation of a lifetime. 



The respectable millwright of former years had already to 

 enlarge his scope of knowledge, and become a steam-engine 

 builder ; having made himself master of the construction of simple 

 forms of high-pressure engines, he has had to go to school again, 

 to study the laws of condensation and of the expansive action of 

 steam, in order to produce an engine using only a fractional 

 amount of the fuel which his customers were willing to expend in 

 former years for a given effect ; he now has to study the laws of 

 electricity and understand the construction of dynamo-electric 

 machines, in order to be able to transmit and distribute his steam 

 power more readily than could be accomplished by means of 

 wheels and belts. But even his condensing steam-engine with 

 variable expansion, of which he is so justly proud to-day, will no 

 longer be acceptable to his client to-morrow, when it will be made 

 clear to him, by the light of thermo-dynamics, that even the best 

 of steam-engines utilises barely a seventh part of the heat-energy 

 residing in fuel, and that the attainment of perhaps three-fourths 

 of that ultimate limit will be required of him. 



Analogous changes threaten to invade almost every existing 

 branch of industry, and it is necessary for every one of you to be 

 prepared for such changes. 



The practical man of former days will have to yield his place to 

 the unbiassed worker who with open mind is prepared for every 

 forward step as it arises. For this purpose it is necessary that he 

 should possess, beyond the mere practical knowledge of his trade, 

 a clear appreciation of the principles of action underlying each 

 operation, and such general acquaintance with the laws of 

 chemistry and physical science as will make it easy for him to 

 adapt himself to the new order of things. 



In order to be so prepared, it is by no means necessary that you 



VOL. III. U 



