viii PREFACE. 



tinued. The additions and corrections in the present (eighth) edition, 

 which are not very considerable, are chiefly such as have been suggested 

 by Professor Bain's " Logic," a book of great merit and value. Mr. Bain's 

 view of the science is essentially the same with that taken in the present 

 treatise, the differences of opinion being few and unimportant compared 

 with the agreements ; and he has not only enriched the exposition by many 

 applications and illustrative details, but has appended to it a minute and 

 very valuable discussion of the logical principles specially applicable to 

 each of the sciences — a task for which the encyclopedical character of his 

 knowledge peculiarly qualified him. I have in several instances made use 

 of his exposition to improve my own, by adopting, and occasionally by 

 controverting, matter contained in his treatise. 



The longest of the additions belongs to the chapter on Causation, and is 

 a discussion of the question how far, if at all, the ordinary mode of stating 

 the law of Cause and Effect requires modification to adapt it to the new 

 doctrine of the Conservation of Force — a point still more fully and elabo- 

 rately treated in Mr. Bain's work. 



