WATER MASSES AND CURRENTS OF THE OCEANS 165 



so that at the coast of Cuba the sea level is about 45 cm higher than at the 

 American mainland. 



The character of the currents in the Straits of Florida was estab- 

 lished by the outstanding measurements which, in the years 1885 to 1889, 

 were made by the U. S. Coast and Geodetic Survey from the survey vessel 

 Blake, commanded by J. E. Pillsbury. Pillsbury's current observations, 

 which were carried out from a vessel anchored in deep water in a swift 

 stream, are among the classical data in physical oceanography, not so 

 much because they give complete information as to the average currents, 

 but mainly because they made possible a convincing demonstration of the 

 correctness of the later methods used for computing relative currents. 

 The upper right-hand graph in fig. 26 (p. Ill) shows the observed average 

 velocity distribution in a section through the narrowest part of the 

 Straits of Florida between Fowey Rocks, south of Miami, Florida, and 

 Gun Cay, south of Bimini Islands, as plotted by Wtist from Pillsbury's 

 data. To the left are shown the corresponding distributions of tempera- 

 ture and salinity as represented by Wiist on the basis of temperature 

 measurements made by Bartlett on board the Blake in 1878 and published 

 by Agassiz in 1888, and of temperature and salinity observations on board 

 the U. S. Coast and Geodetic Survey vessel Bache in 1914. By means of 

 these data, Wtist has computed the velocity distribution which is shown 

 in the lower right-hand graph in fig. 26 and which is in remarkable agree- 

 ment with the observed distribution. In order to arrive at absolute 

 values of the velocity, Wtist had to assume a known velocity at some 

 depth, and, on the basis of the distribution of temperature and salinity, he 

 assumed an inclined surface of no motion at some distance from the 

 bottom, as shown by the curves marked 0. These curves nearly coincide 

 with the curve of zero velocity as derived from Pillsbury's measurements. 

 Thus, a complete correspondence is found between observed and com- 

 puted currents, and this single example, therefore, has greatly contributed 

 to increasing the confidence in the correctness of computed currents in 

 general. 



On the basis of measurements and computations, Wtist finds that the 

 average transport of water through the Straits of Florida is 26 million 

 m^/sec. The transport probably shows an annual variation and may 

 differ from year to year, but so far little is known about such fluctuations. 



In its further course the Florida Current closely follows the continental 

 slope, flowing most swiftly directly along the slope. The shallow coastal 

 waters to the left of the Florida Current remain more or less at rest, and 

 often the transition from these waters to the blue waters of the Florida 

 Current is so abrupt that the border of the Florida Current can be seen as 

 a line stretching from horizon to horizon. After emerging from the 

 Straits of Florida the current is soon joined by the Antilles Current, 

 which, according to Wtist, carries about 12 million mVsec. Owing to the 



