FARADAY. 343 



all the ages of the human race Nature will find room for 

 both the philosophical experimenter and the mathematician. 

 Faraday entered his protest against the foregoing statement 

 by labelling his investigations " Experimental Researches 

 in Electricity." They were completed in 1854, and three 

 volumes of them have been published. For the sake of 

 reference he numbered every paragraph, the last number 

 being 3,362. In 1859 he collected and published a fourth 

 volume of papers under the title, " Experimental Researches 

 in Chemistry and Physics." Thus the apostle of experi- 

 ment magnified his office. 



The second volume of the Researches embraces memoirs 

 on the Electricity of the Gymnotus ; on the Source of Power 

 in the Voltaic Pile ; on the Electricity evolved by the Friction 

 of Water and Steam, in which the phenomena and principles 

 of Sir William Armstrong's Hydro-electric machine are 

 described and developed ; a paper on Magnetic Rotations, 

 and Faraday's letters in relation to the controversy it 

 aroused. The contribution of the most permanent value 

 here is that on the Source of Power in the Voltaic Pile. By 

 it the Contact Theory, pure and simple, was totally over- 

 thrown, and the necessity of chemical action to the main- 

 tenance of the current demonstrated. 



The third volume of the Researches opens with a me- 

 moir entitled, " The Magnetization of Light, and the Illu- 

 mination of Magnetic Lines of Force." It is difficult even 

 now to affix a definite meaning to this title ; but the dis- 

 covery of the rotation of the plane of polarization which it 

 announced seems pregnant with great results. The writ- 

 ings of William Thomson on the theoretic aspects of the 

 discovery ; the excellent electro-dynamic measurements of 

 Wilhelm Weber, which are models of experimental com- 

 pleteness and skill ; Weber's labors in conjunction with his 

 lamented friend Kohlrausch above all, the researches of 

 Clerk Maxwell on the Electro-magnetic Theory of Light 



