ON THE LIGHT THROWN BY RECENT INVESTIGATIONS 

 ON ELECTRICITY ON THE RELATION BETWEEN MAT- 

 TER AND ETHER.« 



By J. J. Thomson, D. Sc, F. R. S., 

 Cavendish Professor of Experimental Physics in the University of Camhridgc. 



Wlien I received the invitation to give the Adamson memorial lec- 

 ture I felt considerable hesitation about accepting it. I felt there 

 was some incongruity in a lecture founded in memory of a great 

 master of metaphysics being given by one who had no qualifications 

 to speak on that subject. I was reassured, however, when I remem- 

 bered how wide were Professor Adamson 's sympathies with all forms 

 of intellectual activity and how far-reaching is the subject of meta- 

 physics. There is indeed one part of physical science where the 

 problems are very analogous to those dealt with by the metaphysician, 

 for just as it is the object of the latter to find the fewest and simplest 

 conceptions which will cover mental phenomena, so there is one 

 branch of physics which is concerned not so much with the discovery 

 of new phenomena or the commercial application of old ones, as with 

 the discussion of conceptions able to link together phenomena appar- 

 ently as diverse as those of light and electricity, sound, and mechanics, 

 heat and chemical action. To some men this side of physics is pecu- 

 liarly attractive; they find in the physical universe with its myriad 

 phenomena and apparent complexity a problem of inexhaustible and 

 irresistible fascination. Their minds chafe under the diversity and 

 complexity they see around them, and they are driven to seek a point 

 of view from which phenomena as diverse as those of light, heat, 

 electricity, and chemical action appear as different manifestations of 

 a few general principles. Regarding the universe as a machine, such 

 men are interested not so much in what it can do as in how it works 

 and how it is made ; and when they have succeeded, to their own satis- 

 faction at any rate, in solving even a minute portion of this problem 

 they experience a delight which makes the question " Wliat is the 



''The Adamson lecture delivered at Victoria University of Manchester, Eng- 

 land, November 4, 1907. Manchester University Lectures, No. 8. University 

 Press, 1908. Reprinted by permission of the author and the publications com- 

 mittee of the university. 



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