Geogrwphy of the Sea. 143 



covered along the east coast of Florida, while of those thi*own 

 out east of the axis not a single one was heard from. As a 

 rule it was found that the stronger the current the more constant 

 the direction and the deeper the stratum. Remarkable fluctua- 

 tions in the flow near the axis were noted, the velocity increasing 

 sometimes one knot in ten or fifteen minutes, and then as sud- 

 denly decreasing again. Lieutenant Pillsbury attributes this, 

 however, to a serpentine movement of the maximum flow, which 

 would sometimes strike the station occupied by the Blake. The 

 edge of the stream was found at about 30 miles south of Re- 

 becca Shoal light-house. 



Between Yucatan and Cape San Antonio the stream was found 

 flowing about north, and the line of maximum velocity corresponds 

 on the average to lO'' before and to 2'^ 20"' after the moon's tran- 

 sit. The excessive variations were like those in Florida Strait, on 

 the west side of the stream, and the maximum velocity of 6:^ 

 knots was found about 5 miles off the 100-fathom line of Yuca- 

 tan Bank. The eastern edge of the stream lies about 20 miles 

 west of Cape San Antonio, and between this edge and the island, 

 eddy currents exist. At the time the easternmost station in 

 this section was first occupied, the declination of the moon was 

 low and the set of the surface current north-easterly. At a high 

 south declination of the moon the surface current was found 

 south-easterly in direction, and east or south-east below the sur- 

 face. The normal flow below the surface was in each case from 

 the Qulf into the Caribbean Sea, and this makes it probable that 

 the station was situated inshore of the average limit of the 

 stream. On Cape San Antonio Bank the currents are tidal, 

 flood running northward and ebb southward. On the Yucatan 

 Bank the currents were also tidal, but as the edge of the bank 

 is approached the stronger flow of the Gulf Stream predominates. 

 The monthly variation in velocity, which was found clearly de- 

 fined at the first two sections occupied, appeared at this section 

 to be obliterated by anomalies not existing at the former. 



Off Cape Hatteras the Blake accomplished the remarkable feat 

 of remaining at anchor in 1,852 fathoms, and this with a surface 

 cui-rent of over 4 knots. Two stations were occupied, and similar 

 variations in velocity were observed as at the other stations. The 

 notable feature at this station was the discovery of tidal action 

 beneath the Gulf Stream, the currents at 200 fathoms depth 

 changing their direction very regularly, the average current flow- 



