58 



INTERNATIONAL ASPECTS OF OCEANOGRAPHY 



question of changes in sea level which is of basic 

 importance in connection with the coral reef 

 problem. 



Quite apart from the purely tidal problems for 

 which tide observations are necessary, such ob- 

 servations furnish the basic data for problems of a 

 wider scope. One of these may be mentioned here, 

 namely, that relating to sea level. From long 

 continued tide observations it can be determined 

 whether the relative elevations of land to sea at 

 any given place are changing. This problem is 

 obxaously of importance in various practical and 

 theoretical fields. 



Two tidal bibliographical undertakings which 

 are now being carried out on a comprehensive 



scale should be mentioned in this connection. The 

 first, by the Committee on Tides of the Association 

 Internationale d'Oceanographie Physique. This 

 bibliography lists in a concise form all the publica- 

 tions issued during a period of years under definite 

 groupings which are of especial value to research 

 students of the subject. The second is the List of 

 Harmonic Constants issued from time to time by 

 the International Hydrographic Bureau, which 

 covers the whole world. Mention should also be 

 made of a publication on Sea Level and Its Varia- 

 tions which will give the monthly and annual values 

 of sea level at various tide stations throughout the 

 world and which is now in press, being published by 

 the above-named Committee on Tides. 



