Fig. i.— H.M.S. Challenger, i 873-1876. 



PREFACE 



Not seldom those who are engaged in oceanographic 

 work are asked by someone about to start on a long 

 voyage : " How can I do some work for science ? I 

 don't know anything about it ; where can I ' read it 

 up ' ?" Such seekers after knowledge might often do 

 most valuable work, even in waters which they would 

 expect to be quite well known. In this study yachts- 

 men, and officers of the Royal Navy, who are apt to 

 find time heavy on their hands in port or on a foreign 

 station, could enjoy an ever-fresh interest in the sea, 

 its workings, and its inhabitants ; even officers of the 

 Merchant Service could find time to help, especially 

 in meteorological and surface-water work. To all such 



