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SCIENCK 



[N. S. Vol. II. No. 52. 



representative of this rare combination. 

 When his attention was first drawn to Far- 

 aday's work he was fortunately still out of 

 the hearing distance of the seductive voice 

 of the old ' direct-action-at-a-distance-theo- 

 ries.' I say fortunatelj^, for, as Hertz* ob- 

 served once in his characteristic way, " he 

 who once strayed into the magic circle of 

 these remained a captive there." Maxwell 

 was born in June, 1831. Faraday an- 

 nounced his first discovery in magneto- 

 electric induction in November of the same 

 year. William Thomson, now Lord Kel- 

 vin, was then only ten years old, " Before 

 I began the study of electricity," says Max- 

 well, f " I resolved to read no mathematics 

 on the subject till I had first read through 

 Faraday's ' Experimental Eesearches on 

 Electricity.' I was aware that there was 

 supposed to be a difierence between Fara- 

 day's way of conceiving phenomena and 

 that of the mathematicians, so that neither 

 he nor they were satisfied with each other's 

 language. I had also the conviction that 

 this discrepancy did not arise from either 

 party being wrong. I was first convinced 

 of this by Sir William Thomson, to whose 

 advice and assistance, as well as to his pub- 

 lished papers, I owe most of what I have 

 learned on the subject." 



Maxwell was barely twenty when he first 

 took up the study of Faraday. Sir Wil- 

 liam Thomson was twenty-four when he 

 first announced, in 1845, in a paper ' On 

 the Elementary Laws of Statical Electric- 

 ity ' (papers on ' Electrostatics and Magne- 

 tism,' Article II.), his strong inclination 

 toward the view of Farada3^ But Thom- 

 son played at that time too prominent a 

 part in the establishment of the Principle 

 of Conservation of Energy and the Me- 

 chanical Theory of Heat to allow Fara- 

 day's splendid discoveries to occupy his at- 



*1. c. 



fTreatise on Electricity and Magnetism ; preface, 

 p. ix. 



tention completely. Maxwell threw his 

 whole young heart and soul into the study 

 of Faraday's ' Experimental Researches.' 

 It was only a year after he took his degree 

 at Cambridge when his first essay ' On 

 Faraday's Lines of Force '* appeared. This 

 essay and his second essay on the same 

 subject, ' Physical Lines of Force, 'f are the 

 forerunners of his gi-eat memoir ' On a Dy- 

 namical Theory of the Electromagnetic 

 Field.' X In his ' Treatise on Electricity 

 and Magnetism ' § the views elaborated in 

 these essays are presented in a somewhat 

 different form and compared to the views 

 of some of the older theories. ' The lines 

 of force,' quoting the words of Hertz, ' as 

 Faraday called the forces considered as in- 

 dependent entities stood before his mind's 

 eye as conditions in and of the space, as 

 stresses, as vortices, as fluxes, as something 

 or another * * .' The first problem, there- 

 fore, which confronted Maxwell in his 

 undertaking to express Faraday's views in 

 terms of the terminology of the accepted 

 mathematical theories at that time was 

 evidently this : What is the physical con- 

 stitution of the medium whose conditions 

 of stress and of motion manifest themselves 

 as electric and magnetic forces, that is, as 

 lines or tubes of electric and of magnetic 

 force ? The first and the second essay give 

 strikingly original mechanical pictures il- 

 lustrating the properties of the medium 

 which will fulfill most of the essential re- 

 quirements. It would lead us too far to 

 enter into a discussion of the beautiful 

 mechanical models which represent Max- 

 well's earliest attempts to explain Faraday's 

 view of the activities going on in an elec- 

 tromagnetic field. A popular account of 

 this phase of Maxwell's work will be found 



* Cambridge Phil. Transact., Dec. 10, 1855. 

 t Philosoph. Mag., March, April and May, 1861 ; 

 Jan., Feb. 1862. 

 t Royal Soc. Transact., Oct., 1864. 

 i Clarendon Press, Oxford, 1873. 



