Fbbbuaby 24, 1911] 



SCIENCE 



315 



velocity and direction ol the flow on the surface 

 and at various depths by means of a current 

 meter. Many hundreds of observations were 

 taken in the straits of Florida between Fowey 

 Kocks and the Bahamas, between Havana and 

 the Florida reefs, in the Straits of Yucatan, in 

 the Equatorial Current between Tobago and Bar- 

 badoes, in all the passages between the West 

 Indian Islands and off Cape Hatteras. 



The section oflf Fowey Rocks was studied dur- 

 ing two winter seasons and at other times for 

 brief periods. This is the narrowest part of the 

 Straits of Florida, being about 42 miles in width. 

 On the west side the bottom descends with fairly 

 regular slope to 400 fathoms, at 15 miles distant, 

 while on the east side 400 fathoms is found at 

 but eight miles from the shore. Anchorages were 

 made at approximately seven-mile intervals across 

 the straits. The bottom was found to be branch 

 coral and broken shells at the anchorage nearest 

 the Bahamas, and there was every evidence from 

 the observations that the current reached the bot- 

 tom here. The stream oS Havana flows east, 

 while off Fowey Kocks it has changed its direction 

 80°, and the inertia of the water in making the 

 turn forces the current to impinge upon the con- 

 fining bank and carries it to the bottom. Between 

 this point and the western slope the observations 

 showed an average current only to about 300 

 fathoms depth, while on the western slope itself 

 the current sometimes reached the bottom and 

 sometimes a negative current was observed. At 

 all anchorages escept the easternmost, mud was 

 brought up by dredge and frequently on the 

 anchor. At eleven and one half miles east of 

 Fowey Rocks there is an outcropping of rock on 

 which an anchor fouled three times, making it 

 necessary to cut the anchoring rope to get under- 

 way, but at other places the bottom was soft. 

 On both sides of the straits the current at times 

 was found to be flowing north as far out as a 

 depth of 10 fathoms or even further off shore. 



It has been stated that the presence of gulf 

 seaweeds near Nantucket shows the Gulf Stream 

 to be flowing there. The Gulf Stream is partly 

 caused by the friction of the trade-winds on the 

 surface of the ocean, and partly by the break of 

 the wave which throws a certain amount of water 

 from its crest into the trough. As the trades are 

 persistent, this becomes a simultaneous movement 

 of the whole surface of the sea within trade-wind 

 limits. Gulf seaweed floats with the current, but 

 it is thrown to leeward by the waves faster than 

 any ordinary current can carry it, or when there 



is no current at all. The water on the Florida 

 reefs about Key West are of milky appearance, 

 while a northerly breeze is blowing which stirs up 

 the bottom coral mud. A southerly breeze brings 

 in the clear water of the Gulf Stream simply by 

 the break of the waves, but no current accom- 

 panies it. 



The Grenadine Bank extends from Grenada to 

 the Island of St. Vincent and is in the direct line 

 of flow of the trade wind current outside the 

 Caribbean. An anchorage in 17 fathoms near its 

 outside edge showed no current crossing the bank, 

 but the break of the waves was all the time carry- 

 ing water into the Caribbean across the shoal. 



As the discussion was extended to a considera- 

 tion of the general effects of oceanic currents on 

 deposition, Mr. T. Wayland Vaughan called at- 

 tention to the investigations Rear Admiral Sir 

 W. J. L. Wharton' made around the islands of the 

 Ellice Group and on submarine banks in that 

 region. According to this authority, fine mud 

 and sand may be moved to a depth of 80 fathoms, 

 and there is evidence of the chafing of cables to a 

 depth of 260 fathoms; "volcanic ash can be 

 moved at depths of 30 fathoms or more when 

 exposed to the action of waves in an otherwise 

 deep sea over which strong winds are continvially 

 blowing." 



Professor J. Stanley Gardiner" has described 

 the submarine platform on which the Maldive and 

 Laccadive archipelagoes stand, and has called 

 attention to the generally hard bottom on it. 

 This platform occupies a level about 200 fathoms 

 below sea level, and he says, " there is little 

 doubt but that it is surrounded with precipitous 

 walls or a steep slope for an additional 600 

 fathoms at least." Professor Gardiner is of the 

 opinion that this platform was formed by marine 

 erosion to the depth of 200 fathoms below sea 

 level. He states, " there is little doubt but that 

 currents may extend to considerable depth and 

 sweep the ocean floor quite bare. Indeed, wherever 

 in the ocean a rocky bottom is found, its char- 

 acter is probably due to an ocean current." 



Dr. Paul Bartsch discussed the distribution of 

 the recent marine mollusks with a view to throw- 

 ing some light upon past conditions. He pre- 

 sented a map showing the extent of the existing 

 faunal areas and called special attention to the 



^'Nature, LV., 1897, "Foundations of Coral 

 Atolls." 



^ " The Fauna and Geography of the Maldive 

 and Laccadive Archipelagoes," Vol. 1, Pt. 2, pp. 

 172, 173. 



