508 G. H. DREW. 



Channel is of steadily increasing depth, up to 2200 fathoms at its 

 junction with the still deeper water of the Atlantic ; the Providence 

 N.W. Channel becomes shallower at its junction with the Straits of 

 Florida, and between Great Isaac and the western end of Bahama 

 Island is only between 200 and 300 fathoms in depth. 



The surface water of the Tongue of the Ocean, except along the 

 coast of Andros, is everywhere continuous with that overlyifag the 

 thousands of square miles of shallows forming the Great Bahama 

 Bank, and the flats and cays lying to the north and west of the 

 Exuma Islands, whereas the deeper water is only connected with the 

 outer ocean by the comparatively narrow entrance between New 

 Providence and the north of Andros, leading, after a turn of about 

 90°, into the Providence N.E. and N.W. Channels. 



The Laboratory from wliich this work was done was established at 

 Golding Cay, at the eastern mouth of the South Bight of Andros ; this 

 position was especially suitable for the work, as by running out 

 a few miles in a direction at right angles to the coast-line the middle 

 of the Tongue of the Ocean could soon be reached, and also the mud- 

 flats to the west of the island were readily accessible by water, as the 

 South Bight runs right through the island to the west coast. In this 

 region the tides are not strong, the average rise and fall being from 

 2 to 3 feet. Much difficulty was experienced in getting any definite 

 information as to the set of currents in the Tongue; our local pilot 

 stated that a current would set in a southerly direction for weeks 

 at a time, and then without any apparent reason or change of wind 

 would reverse and set in a northerly direction for several weeks, but 

 such information derived from the negro natives cannot be relied on. 

 When taking observations on May 8th, May 11th, and May 23rd, we 

 experienced a distinct southerly drift on each occasion, but the amount 

 of this drift was not determined, and in addition the drift caused 

 by the wind was an unknown factor. On May 8th the wind was 

 S.S.E., of about force 1 at 8.30 a.m., freshening to about force 3 at 

 10.30 a.m. ; a rough estimate from the landfall on returning gave the 

 drift of the boat as about 2 miles south during the four hours occupied 

 in working the station; the boat had a large awning and exposed 

 a considerable area to the wind, and had drifted this distance against 

 the wind, so it would seem that on that occasion there must have 

 been a strong current setting south. 



Andros Island consists of a limestone formation, the exact nature of 

 which has been dealt with by Way land Vaughan (17). The greater 

 part of the island is very flat, and is only elevated a few feet 

 above sea-level : a few irregular undulations, never more than 100 feet 



