KINETIC OR MECHANICAL VIEW OF NATURE. 73 



This suggestion was not carried out for some time, 

 and then not by Thomson himself, but, at his instiga- 

 tion, by Clerk Maxwell. In the meantime, however, 

 Thomson added another step to the one already taken, by 

 bringing recent discoveries of Faraday, as well as his 



point out how the elementary ex- 

 perimental data referring to elec- 

 trical charges, as well as to mag- 

 netic bodies, can be mathematically 

 expressed equally well by the con- 

 ceptions of Coulomb and Poisson 

 and by those of conduction and flow, 

 which are more in conformity with 

 Faraday's physical ideas : neither 

 of the mathematical analogies, of 

 attraction at a distance or of con- 

 duction through an intervening 

 medium, being sufficient for a 

 physical theory. These papers con- 

 tain further the record of the 

 gradual growth in the author's 

 mind of the kinetic out of the 

 statical view of natural phenomena. 

 Thomson was the first (1851) to 

 introduce the terms " field " and 

 " lines of force " into mathemati- 

 cal literature, adopting them from 

 Faraday. They have since become 

 indispensable not only to the electri- 

 cian but likewise to the mathema- 

 tician ; forming, as it were, a unify- 

 ing term for apparently distant 

 regions of physical phenomena, and 

 being introduced as fundamental 

 notions at the beginning of dynami- 

 cal treatises. See, for instance, the 

 article by M. Abraham entitled 

 " Geometrische Grundbegriffe," in 

 the second part of the fourth volume 

 of the ' Encyclopadie der mathe- 

 Tnatischen Wissenschaften,' Leipzig, 

 Teubner, 1901. Independently and 

 quite unknown to Faraday, or to 

 each other, two eminent mathe- 

 maticians, Sir \V. R. Hamilton at 

 Dublin and Herrmann Grasstnann 

 at Stettin, were elaborating, be- 

 tween 1835 and 1845, the geo- 

 metrical conceptions and vocabulary 



which are required in the repre- 

 sentation of " directed " quantities. 

 Their expositions have since become 

 much simplified, and now form, 

 under the title of "vector an- 

 alysis," an indispensable geometrical 

 instrument. The gradual evolution 

 of the kinetic view of physical 

 phenomena (which here concerns us 

 most) in the memoirs of Thomson 

 is most remarkable. Inter alia, he 

 made a communication in 1847 to 

 the British Association at Oxford, 

 in which he dealt with the phe- 

 nomena of terrestrial magnetism, 

 stating that "it becomes an in- 

 teresting question whether mere 

 electric currents could produce the 

 actual phenomena observed. Am- 

 pere's electro-magnetic theory leads 

 us to an affirmative answer which 

 must be regarded as merely theor- 

 etical ; for it is absolutely impossible 

 to conceive of the currents which he 

 describes round the molecules of 

 matter as having a physical exist- 

 ence" (Reprint, 2nd ed. , p. 469). 

 On this passage he himself remarks 

 in 1872 : " From twenty to twenty- 

 five years ago, I had no belief 

 in the reality of this [Ampere's] 

 theory ; but I did not then know 

 that motion is the very essence of 

 what has hitherto been called 

 matter. At the 1847 meeting of 

 the British Association in Oxford 

 I learned from Joule the dynamical 

 theory of heat, and was forced to 

 abandon at once many, and gradu- 

 ally from year to year all other, 

 statical preconceptions regarding 

 the ultimate causes of apparently 

 statical phenomena" (ibid., p. 423 

 note). 



