PREFACE 



TO THE SECOND EDITION. 



A considerable time has now elapsed since the 

 still unsold copies of the first edition of this book 

 were destroyed by fire at the publishers. The 

 demand for the book had at that time by no means 

 ceased, and I was considering the advisability of 

 preparing a second edition for the press when it 

 came before my notice that there was still much 

 valuable matter which might be introduced into the 

 Appendix, in addition to those amendments which, 

 as I already knew, might be made in the body of 

 the work. This combination of circumstances led 

 to my determining, under the advice of friends, to 

 bring out a new edition; and that my purpose should 

 have been so slow of fulfilment as it unfortunately 

 has been is mainly due to the fact that I have been 

 obliged to spend at intervals much of the interven- 

 ing time abroad, during which periods progress with 

 the work in hand has proved almost impossible. 



