242 INTRODUCTION TO SCIENCE 



single idea, advanced in a masterly treatise by 

 Auguste KeTcuU in the year 1865.'" 



It is a commonplace that the developments of 

 steam-power, electric Telegraphy, Telephony, and 

 Dynamo-electrical machinery, which have changed 

 human life so markedly, have come about in 

 association with new theoretical developments in 

 the sciences of heat and electricity. To substan- 

 tiate this precisely is not difficult, but an analo- 

 gous case will, we think, suffice for demonstration. 

 When Prof. William Thomson published, hi 1853, 

 in the Philosophical Magazine, a stiff bit of 

 mathematical analysis, which laid the founda- 

 tion of the theory of electric oscillations, there 

 can have been few who saw in it the basis of 

 wireless telegraphy. 



In this connection, it is very interesting to 

 hear Lord Kelvin's own opinion, for he excelled 

 alike in theoretical insight and in practical appli- 

 cation. After speaking of "the vast resources 

 which we derive from direct applications of mod- 

 ern science," "of the immense practical impor- 

 tance of the principles of Natural Philosophy," 

 he says: "We must not, however, by considera- 

 tions of this kind, be led to regard applications 

 to the ordinary purposes of life as the proper 

 object and end of science. Nothing could more 

 effectually stop the advancement of knowledge 

 than the prevalence of such views; even the 



