THE THEORY OF ENERGY AND THE LIVING WORLD. 525 



others in its essence and in the last analysis of its actions; quite the 

 contrary ! Its nature is still discussed. Some, in consideration of its 

 immense velocity of transmission and its similarity to light, have con- 

 sidered it to be a veritable flow of the ether, like Father Secchi, who 

 assimilated it with the flow of water in a conduit. According to this 

 view, electrical work is comparable with that done by water pressure 

 in the hydraulic motor. Thus, electricity itself would not be a form of 

 energy, but only a vehicle for energy. However, most physicists follow 

 the view of Clausius and more recently of Hertz, who held that it is not 

 energy itself which is thus propagated, but a vibratory motion. Be 

 that as it may, the most characteristic property of electrical energy and 

 that which renders it of the greatest value is its extraordinary capac- 

 ity for transformation. All other known forms of energy may be con- 

 verted into electrical energy and conversely with tbe greatest facility. 

 This extreme docility assigns to electricity the role of intermediary in 

 the transformation of the other less tractable agents. Mechanical 

 energy, for example, is not readily transformed into radiant energy. 

 A fall of water can not be directly utilized for lighting purposes, but 

 in the installation of industrial lighting plants; the water power is first 

 caused to drive a dynamo, which then feeds the incandescent or arc 

 lights. Otherwise unavailable mechanical work is constantly being 

 turned into electrical energy, and the latter into heat and light. Elec- 

 tricity has taken up the post of an intermediary agent. 



And now if we wish to develop the programme of the science of 

 energy it is necessary to indicate the second great principle, that which 

 according to Eobert Mayer controls all its transformations, the princi- 

 ple of Carnot. Next it should be shown by some numerical example, 

 some concrete illustration, how contemporary science has taken account 

 of the nature and the transformations of energy. Following this the 

 kinetic theory should be expounded. The universe of matter according 

 to this theory is conceived as animated by two kinds of motions, the 

 visible and the molecular. An historical treatment should be followed 

 of the manner in which this hypothesis was introduced in physical 

 science owing to the necessity of taking account of the phenomena of 

 the propagation of light; how it was formed in the study of heat; how 

 made precise, thanks to Clausius and Maxwell, in the case of gases, 

 and how, finally, it has been extended to the manifestations of elec- 

 tricity and magnetism. We can not undertake this task here for two 

 reasons. The first is that the kinetic theory, which has scarcely yet, 

 through infinite pains, arrived at its full elaboration, already shows 

 signs of decadence and ruin. Physical theorists of one school already 

 express doubt of the existence of the ether, the medium necessary for 

 the propagation of the radiant energy, and they deny that electricity 

 is a mode of motion or even that heat and light are such. They deign 

 to erect nothing upon the ruins of this theory, which has become so 

 firmly rooted upon the contemporary mind that it is in some sort a part 



