148 SCIENTIFIC THOUGHT. 



in fact, an electro-magnetic disturbance of very short 

 wave length. I also mentioned above how this sug- 

 gestion received a brilliant confirmation from Hertz when 

 he succeeded in exhibiting electro-magnetic waves, which 

 in travelling through space, though not luminous, showed 

 all the properties peculiar to light waves, such as re- 

 flexion, refraction, polarisation, &c. 



Whilst in this country, during the period from 1850 

 to 1870, the Scotch school of natural philosophy was 

 thus occupied in rebuilding the whole edifice of physical 

 science on the new basis afforded by the energy ideas, 

 Clausius in Germany worked at the further elaboration 

 of the dynamical theory of heat, and, as I stated above, 

 at the kinetic theory of gases, without abandoning the 

 astronomical view of natural phenomena, which, with its 

 supposition of forces acting at a distance, still almost 

 exclusively governed theoretical physics and chemistry 

 abroad. No one did more to emphasise the difference 

 between this and Faraday's views than Clerk Maxwell, 

 who had welded the latter into a consistent scheme by 

 means of the conception of energy. About the year 

 1870 Helmholtz again appeared as a leader of scien- 

 tific thought in this domain, and placed himself at 

 the head of a movement which by degrees almost 

 completely swept away the older ideas. It was by him 

 or at his suggestion that many of the more modern 

 English works of science were translated l and intro- 



1 Notably Thomson and Tait's natural philosophers of eminent 



'Natural Philosophy,' and several , rank abroad who broke with the 



of Tyndall's well - known more older habit of exclusiveness which 



popular works on ' Sound,' ' Heat,' ! clung to academic teachers in Ger- 



and ' Fragments of Science. ' Helm- ' many, and who followed the English 



holtz was also one of the first example set by the " Addresses " of 



