GENERAL PLAN OF THE SERIES. 



This Series is primarily designed to aid the University Extension 

 Movement throughout Great Britain and America, and to supply 

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

 reference, in connection with the authorised Courses of Lectures. 



Volumes dealing with separate sections of Literature, Science, 

 Philosophy, History, and Art have been assigned to representative 

 literary men, to University Professors, or to Extension Lecturers 

 connected with Oxford, Cambridge, London, and the Universities of 

 Scotland and Ireland. 



The Matiuals are not intended for purposes of Elementary Educa- 

 tion, but for Students zvho have made some advance in the subjects 

 dealt with. The statement of details is meant to illustrate the 

 working of general laws, and the development of principles ; while 

 the historical evolution of the subject dealt with is kept in view, 

 along with its philosophical significance. 



The remarkable success which has attended University Extension 

 in Britaiti 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 in the 

 larger centres of populatio?i, while all over the country there arc 

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

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

 general reader zvith the same kind of teaching 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 inte?ided to he contribution's to the Literature 

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

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

 general rather than a special want. 



