412 FEAGMENTS OF SCIENCE. 



find room for both the philosophical experimenter and 

 the mathematician. Faraday entered his protest against 

 the foregoing statement by labelling his investigations 

 ' Experimental Eesearches in Electricity.' They were 

 completed in 1854, and three volumes of them have 

 been published. For the sake of reference, he num- 

 bered every paragraph, the last number being 3,362. 

 In 1859 he collected and published a fourth volume 

 of papers, under the title, 'Experimental Eesearches 

 in Chemistry and Physics.' Thus did this apostle of 

 experiment illustrate its power, and magnify 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 Arm- 

 strong's Hydro-electric machine are described and de- 

 veloped; a paper on Magnetic Rotations, and Faraday's 

 letters in relation to the controversy it aroused. The 

 contribution of 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 

 maintenance of the current demonstrated. 



The third volume of the Researches opens with a 

 memoir entitled ' The Magnetisation of Light,' and the 

 ' Illumination of Magnetic Lines of Force.' It is diffi- 

 cult even now to affix a definite meaning to this title; 

 but the discovery of the rotation of the plane of polari- 

 sation, which it announced, seems pregnant with great 

 results. The writings of William Thomson on the 

 theoretic aspects of the discovery; the excellent electro- 

 dynamic measurements of Wilhelm Weber, which are 

 models of experimental completeness and skill; Weber's 

 labours in conjunction with his lamented friend Kohl- 



