PREFACE xiii 



tion, reflection, and more or. less severe study. Suffice 

 it, therefore, to say that the original teaching which it 

 was our privilege to obtain, the information we derived 

 from the perusal of text-books and works of reference, 

 as well as the ordinary ' serial literature of the period,' 

 and the personal opportunities of gaining knowledge ' at 

 first hand ' which we have enjoyed, have been the source 

 from which any truths they may contain were elaborated. 

 For our indebtedness to all these c non-personal ' sources 

 of knowledge, therefore, we take the opportunity of ex- 

 pressing our warmest thanks, and our sincerest apologies 

 for our inability to mention individual names. 



Moreover, we are well aware and are bound to acknow- 

 ledge that, but for ' these non-personal ' sources of 

 information and the opportunities they have given of 

 daily ' piecing together ' the materials they supplied, it 

 would have been altogether impossible for us to have 

 systematised the facts and deduced the views which we 

 have now, however imperfectly, ventured to put before 

 those capable of appraising their scientific value and 

 their practical bearings. 



THOMAS LOGAN. 



