ON THE PHYSICAL VIEW OF NATURE. 143 



electric currents and magnets, the phenomena of dia- 

 magnetism, Ampere's theory and Weber's basis of 

 electric measurement, Seebeck's production of electric 

 currents by heating in a non-homogeneous conductor, 

 the remarkable phenomena known by the name of 

 Peltier, the electro -dynamic properties of metals, the 

 thermo- elastic properties of matter, were all studied 

 in the light of the new principle, the conservation 

 and transformation of energy. Another very import- 

 ant problem presented itself, viz., the introduction of 

 the new ideas into the higher educational literature, 

 the re -writing of the text -books of science on the 

 basis of the principle of energy, and especially the 

 development of the fundamental notions in mechanics 

 in conformity with the more modern views. Here, 

 then, it became evident that the physical view of 

 natural phenomena, according to which they are all 

 instances of the transformation of energy, could be 

 considered and expounded as a further development of 

 the laws of motion as laid down in Newton's ' Prin- 

 cipia.' It was especially the third law of motion, in 

 which Newton stated the equality of action and re- 

 action, that lent itself to such an interpretation as 

 would at once lead to the wider grasp and deeper 

 insight into natural processes which the principle of 

 energy afforded. Accordingly about the year 1860, 

 when the new ideas on energy had, in the minds of 

 the great pioneers, acquired that importance which 

 has enabled them to become the basis of a more 

 and more comprehensive view the physical view of 

 natural phenomena, the necessity was experienced of 



