EXPLORATIONS, WESTERN ATLANTIC, STEAMER BACHE, 1914. 45 



Straits, and from the southern part of the Gulf along the shore of 

 Cuba, into the southern side of the Straits, as into a funnel. Up- 

 welUng of bottom water against the coast of Florida grows more 

 pronounced as this tremendous mass of water forces its way farther 

 and farther into the ever narrowing and shoaling channel. 



The unity of temperature between the western end of the Straits 

 in 1914; and the Gulf of Mexico as a whole in 1878, is further 

 interesting because it shows that the difference of temperature in 

 the eastern end of the Straits in the two years can not have been due 

 to any intrinsic difference in the reservoir from which the water 

 came, but must have been the result of a greater flow of cold bottom 

 water in 1878 than in 1914. For all that is yet known, this may be 

 a seasonal, not a vicarious or periodic, variation. 



The bankmg up of cold water against Florida is usually classed as 

 the effect of the rotation of the earth, forcing the water out of its 

 course toward the right against Cuba and the Bahama Bank, with 

 consequent upwellmg from the deep layers on the left-hand side of 

 the channel, according to Ekman's (1905) theory (Kjiimmel, 1911, 

 p. 459). The discovery that the cold comparatively fresh water 

 next to Florida is largely true abyssal water from the Gulf of Mexico 

 supports this view. The density profile, Cape Florida to Gun Cay 

 (fig. 46), shows how much lighter, as weU as fresher and colder, the 

 water was on the left than on the right side of the current," an 

 illustration of how effective the deflective force of the earth's rotation 

 is in establishing the distribution of temperature and salinity in a 

 current as rapid as the Florida stream. 



THE COAST WATER OFF CHESAPEAKE BAY. 



Exploration of the coast water was only incidental to the main 

 work of the Bache, but stations 10157-10160 off the mouth of Chesa- 

 peake Bay, and a series of observations taken on the continental 

 shelf in that same general region in January, 1916 (p. 60), by the 

 Bureau of Fisheries steamer Roosevelt, may be discussed here because 

 of their bearing on the general problem of the origin of the coast 

 water and its relationship to the Gulf Stream (Bigelow, 1915, p. 250). 



In January, 1913 {Bache stations), the temperature from the coast 

 out to the 35-meter contour was between 6° and 7°, practically 

 uniform from surface to bottom. The salinity, however, showed 

 considerable vertical range even in the small depth of 18 meters 

 (30.0P/oo on the surface, 33.57Voo on the bottom, station 10157), 

 and at the 35-meter contour the freshest water lay at 20 meters 

 (station 10159), with Salter water both above and below (fig. 48), 



« For discussion of the general prolilem of the effect of the earth's rotation on ocean currents, see Ekman 

 (1905) and McEwen (1912). For an excellent summary of the results on actual ocean currents, see Murray 

 and Hjort (1912), p. 276. 



