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SCIENCE 



[N. S. Vol. XLIII, No. 1115 



field force of the Coast Survey has always given 

 loyal service to the country. If war should come 

 they and their distinguished superintendent will be 

 prompt to offer their services. They will be again 

 ready. May they then find the nation more grate- 

 ful than did those who were detailed from the sur- 

 vey during the Civil War. 



The International Worh of the United States Coast 

 and Geodetic Survey: Dr. Otto Hilgakd Titt- 



MANN. 



Speaking of the international work of the Coast 

 and Geodetic Survey done in direct cooperation 

 with other countries, Dr. Tittmann said that it may 

 justly give satisfaction to the members of the sur- 

 vey that the results of its work are nearly all in- 

 ternational in their scope. 



The hydrographic and tidal surveys are obviously 

 for the benefit of all mankind because they safe- 

 guard the commercial intercourse of nations. Its 

 geodetic work contributes to the knowledge of the 

 earth 's dimensions and constitution. The world 's 

 knowledge of terrestrial magnetism would be in- 

 complete without the record of the observation of 

 magnetic phenomena as they occur in the vast 

 territory inhabited by us and so with those relat- 

 ing to the tides. Thus in the prosecution of its 

 tasks, the survey adds to our knowledge of the 

 planet which we inhabit and thereby furthers the 

 ultimate aim of all civilization, the intellectual 

 development of mankind. 



He then referred to Senator Sumner's speech 

 delivered immediately after the acquisition of 

 Alaska in which Sumner spoke of the north and 

 south boundary of the territory just acquired as 

 extending to the frozen ocean or the "North Pole 

 if you please." Mr. Tittmann evidently believes 

 that the Senator intended to lay the foundation 

 for a claim to any land which might lie between 

 Alaska and the North Pole. He pointed out that 

 Admiral Peary visited the North Pole end of the 

 line, and that during the famous journey he was 

 formally attached to the Coast and Geodetic Sur- 

 vey for the purpose of observing Arctic tides. 



After briefly reviewing the delimitation of the 

 Alaska boundary, extending over a length of 

 about 1,800 miles, by the survey. Dr. Tittmann de- 

 scribed the part taken by the survey in the delimi- 

 tation and remonumenting of our northern and 

 also of the Mexican boundary, undertakings which 

 he considered the most striking of the survey's 

 international accomplishments. 



He then spoke of the relation of the Coast Survey 

 to the International Geodetic Association and its 

 supervision of two small astronomical observa- 



tories for observing the variations of latitude, 

 maintained in this country by the association. He 

 also described the survey's share in the scientific 

 work leading to the establishment of the Interna- 

 tional Bureau of Weights and Measures, pointing 

 out that the directorship of this important bu- 

 reau was offered to the American delegate, Mr. 

 Hilgard, of the Coast and Geodetic Survey, but 

 was declined by him. 



International scientific expeditions made by the 

 survey, including transit of Venus expeditions, 

 and those for observing solar eclipses, were rapidly 

 passed in review by the speaker, who, in conclud- 

 ing, expressed the hope that the next centennial 

 celebration of the Coast and Geodetic Survey 

 might afford as satisfactory a retrospect as the 

 present. 



Oceanic Tides with Special Reference to the Worh 

 of the United States Coast and Geodetic Sur- 

 vey : Dr. Charles Lane Poor. 

 The mathematical theory of the tides begins 

 by assuming a solid earth surrounded by a shal- 

 low, frictionless ocean. In such an ocean the at- 

 traction of the moon would cause waves to travel 

 around the earth from east to west. For many 

 years the complete mathematical solution of this 

 simple problem taxed the ability of the ablest 

 scientists, and when finally solved the solution did 

 not materially advance the theories and explana- 

 tions of the actual tides in the oceans as they exist 

 on the earth. 



To pass from this ideal world to actuality; 

 from a simple all-pervading ocean of uniform 

 depth, to oceans separated by continents, and 

 varying in depth, defies the skill of the mathema- 

 tician. Yet Newton, Laplace and a succession of 

 brilliant mathematicians have all tried to do this; 

 to pass from the simple to the complex. They 

 consider the tides as a world phenomenon — as an 

 ideally simple wave, modified, broken up, and de- 

 layed by the continental barriers; by the varying 

 depths of the oceans. Sir George Darwin consid- 

 ers the great earth tides as formed in the broad, 

 deep waters of the southern Pacific. From here 

 the tidal wave spreads east and west, around Cape 

 Horn and past Cape of Good Hope, and sweeps 

 through the Atlantic at a rate depending solely 

 upon the depth of the water. 



This simple world idea of the tides was evolved 

 and elaborated from observations of the tides of 

 Europe. In the days of Laplace there was little 

 knowledge of the tides in other parts of the 

 world, and it was naturally thought that the Eu- 

 ropean tides were fairly representative. The dy- 



