EDITOR'S PREFACE 



This Series is primarily designed to aid the University Extension 

 Alovement throughout Great Britain and the United States, and to 

 supply the need so widely felt by students, of Text-books for study and 

 reference, in connection with the authorised Courses of Lectures. 



The Manuals differ from those already in existence in that they 

 are not intended for School use, or for examination purposes ; and 

 that their aim is to educate, rather than to inform. The statement 

 of details is meant to illustrate the working of genei-al laws, and the 

 development of principles ; while the historical evolution of the 

 subject dealt with is kept in vieWy along with its philosophical 

 signijicaftce. 



The remarkable success which has attended University Extension 

 in Britain has been partly due to the combination of scientific treat- 

 ment with popularity, and to the union of simplicity with thorough- 

 ness. This movement, however, can only reach those resident i?t the 

 larger centres of population, while all over the country there are 

 thoughtful persons who desire the same kind of teaching. It is for 

 iJiem also that this Series is designed. Its aim is to supply the 

 general reader with the same kind of leachittg as is given in the 

 Lectures, and to reflect the spirit which has characterised the move- 

 ment, viz. the combination of principles with facts, and of methods 

 with results. 



The Manuals are also intended to be contributions to the Literature 

 of the subjects with which they respectively deal, quite apart from 

 University Extension ; and some of them will be found to meet a 

 general rather than a special want. 



They will be issued simultaneously in England and America, 

 Volumes dealing with separate sections of literature. Science, 

 Philosophy, History, and Art have been assigned to representative 

 literary men. 



A list of the works in this Series can be obtained on application to 

 the Publishers. 



