THE AIM OF SCIENCE 47 



of seventy-two, surprised many by a remarkable 

 utterance: "One word characterizes the most 

 strenuous of the efforts for the advancement of 

 science that I have made perseveringly during 

 fifty -five years; that word is failure. I know no 

 more of electric and magnetic force, or of the 

 relation between ether, electricity, and ponder- 

 able matter than I knew and tried to teach my 

 students of natural philosophy fifty years ago 

 in nay first session as Professor." 



It is instructive to inquire from the experts, 

 of course what this indefatigable genius, whose 

 life was a sequence of brilliant successes, meant 

 by speaking of failure. Prof. Silvanus P. Thomp- 

 son in his Life of Lord Kelvin explains the case. 

 "The trend of modern ultra-physics with respect 

 to the constitution of matter is towards the fol- 

 lowing five categories: (1) the ether, that is, the 

 plenum filling space; (2) the electron, conceived 

 as a plexus in the ether, probably of two species; 



(3) the atom, a complex of electrons in the ether; 



(4) the molecule, a specific group of atoms (or in 

 some cases one atom); (5) the mass, an assem- 

 blage of molecules. Energy is involved in the 

 construction of any of these out of any other. 



"Lord Kelvin's effort seems to have been to 

 find a theory to reduce the necessary concepts 

 to the smallest number matter and energy, or, by 

 means of the vortex theory, to ether and energy. 



