Geogrwphy of the Sea. 145 



to E. N. E., except at 65 fathoms depth, where there appeared to 

 be an inward flow. On the western side of the passage, near 

 Santo Domingo, the direction of the currents was between S. S. E, 

 and S. W. by W. But few observations could be taken on 

 account of unfavorable weather. 



In the Windward Passage, on the western side the currents 

 from the surface down to 130 fathoms set in the directions lying 

 in the S. E. quadrant, and at 200 fathoms the direction changed 

 to W. by S. On the eastern side the surface current varied be- 

 tween E. N. E. and E. S. E., with about ^ knot velocity. Varia- 

 tions in the direction similar in extent characterized also the sub- 

 surface currents in the middle and on the eastern side of the 

 passage. 



The average of the observations at these three stations gives 

 but a small volume of water passing in either direction. 



In the old Bahama Channel, at the station north of Cayo 

 Romano (island off the north coast of Cuba) the currents at and 

 near the surface set south of east ; at 65 fathoms, however, the 

 direction varies fi'om about N. W. to E. The deeper current 

 of great volume flowed continually to the north of west with a 

 velocity of over 1-^ knots at depths of 130 and 200 fathoms. 



Outside the Bahamas, to the north of Great Abaco, a slight cur- 

 rent flows about N. W. on the surface and down to 30 fathoms ; 

 at 65 fathoms depth the direction changes to a point more west- 

 erly, and at 130 fathoms to a point more easterly than the set of 

 the surface current. The maximum in the daily variation at this 

 station occurs about 1 2^ after the moon's transit. 



The observations so far as completed by Lieutenant Pillsbury 

 furnish the most valuable data we have at present concerning the 

 Gulf Stream, and it is hoped that further investigation and the 

 analytical treatment of these observations will clearly develop 

 the dynamic laws involved and lead us to a correct theory of cur- 

 rent phenomena in general. 



Tidal Phenomena. 



The causes for many of the inequalities in the tidal elements 

 observed at different places have not yet been satisfactorily ex- 

 plained. The phenomena are dependent on many purely terres- 

 trial conditions. While we are able to ascertain with tolerable 

 accuracy from certain constants, derived from observation, the 

 times and heights of the tides, the problem to compute theoret- 



