PREFACE 



A LARGE part of this volume was already in 

 print when it was decided, and promised in the 

 Preface to Vol. I., that the second volume should 

 include subjects connected with Geology, and the 

 third should be chiefly concerned with Maritime 

 affairs. Accordingly, two hundred pages on 

 navigational subjects were marked " Vol. III." 

 and struck off before any progress was made 

 with Vol. II. Hence Vol. III. now appears 

 before Vol. II., the publishers having advised me 

 that they would not be professionally shocked 

 by such an irregularity. The present volume 

 ends with an article kindly contributed by Capt. 



