On Changes in the Sea and Their Relation to Oi'ganisms. 



221 



The determinations for constructing this curve were made as follows: 

 A wash-bottle of about 500 c.c. capacity was supplied with about 

 400 c.c. of sea-water and immersed in a thermostat. Moistened out- 

 door air was drawn through the wash-bottle by means of a suction- 

 pump until equihbrium was established. The air passed through a 

 very small wash-bottle of sea- water and a copper coil (both immersed 

 in the thermostat) before reaching the 500 c.c. wash-bottle. The 

 analyses were made by the Winkler method, using the same standards 

 as with the other determinations, a correction being applied for the 

 average gas-pressure in the wash-bottle. No correction was made for 

 the vapor tension of water, since it was the same as at the sea surface 

 everywhere. 



4.2 



4.8 



5.0 



5.2 



5.3 



IS 19 20 21 22 23 24 25 26 27. 28 20 30 



Fig. 6. — Curve of equilibrium of Tortugas sea-water with air at 760 mm. barometric pressure; 

 the degrees temperature (18 to 35) are marked on the abscissa and the number of cubic 

 centimeters of oxygen per liter of sea-water (5.3 to 4.0) on the ordinate. 



CURRENTS. 



The surface currents to be considered are: 



(1) The Gulf Stream, which parallels the Florida Keys and then 

 flows toward Cape Hatteras (but only those observations between the 

 latitudes of Miami, Florida, and Wilmington, North Carolina, were 

 in the axis of the stream). 



(2) The countercurrent in shallow water, which flows from Cape 

 Hatteras, along the shore, until it reaches the Florida Keys, when it 

 flows in the Hawk Channel (between the keys and the outer reef) and 

 passes through the Tortugas and out into the Gulf of Mexico. 



