PREFACE. 



THE following essay is an expansion of a paper read before 

 the Aristotelian Society in February, 1906. I have to acknow- 

 ledge the kindness of the Committee, which has permitted me 

 not only to embody here most of my original matter, but also 

 to make use of the type in which it was standing. The work 

 in its present form (with the exception of one or two trifling 

 emendations) was printed in September, 1906, and presented 

 to the University of London as a thesis for the degree of Doctor 

 of Science. 



The results described in the essay were reached in the 

 course of a study of the problems of Science teaching in schools, 

 and are believed to have very definite pedagogical applications. 

 These applications are not considered in the present volume, 

 but, in view of the paucity of writings in English which treat 

 of the pedagogy of Science upon a philosophical basis, I have 

 thought it legitimate to direct the attention of the interested 

 reader to the places where I have discussed some of my topics 

 from the professional point of view. For the same reason I 

 venture to refer to the chapter on Science Teaching in Professor 

 J. W. Adamson's book on The Practice of Instruction. 



The customary acknowledgements that have been made 

 whenever I have appealed consciously to the work of other 

 writers should be supplemented in two particulars. Even my 

 numerous footnote references to the Principles of Mathematics 

 hardly suggest the full amount of the inspiration which I have 

 drawn from the work of the Hon. Bertrand Eussell. I am 



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