EXPLANATION OP OCEAN TEMPERATURE CHART No. 4. 



FOWEY EOCKS LIGHT-HOUSE, FLOEIDA. 

 Observer: John J. Larsek. 



Position. — Fowey Eocks light-house is huilt on Fowey Eocks, which are Jocated very near the northeastern 

 extremity of the Florida Eeefs, about 6 miles southeasterly from Cape Florida, and 23 miles northerly from Carysfort 

 Eeef. These rooks are on the western side of the Straits of Florida, in their northern and narrowest portion, some- 

 times called the Straits of Bernini, the eastern border of which is formed by the northwestern extremity of the Great 

 Bahama Bank. The light-house is situated on the outer edge of the rocks, which lie directly in front of the widest 

 opening to Key Biscayne Bay. Depths of 7 to 16 fathoms occur close to the light; the 100-fathom line is distant only 

 about '2J miles, and the axis of the. Gulf Stream about 24 miles. 



Geographical position.— haiiia&e,, 25° 35' 25" N. ; longitude, 80° 05' 41" W. 



JJepth oficater. — Five feet. 



Sange of temperature.— Mr, 18° (68° to 86°) ; surface, 16°.5 (70° to 8S°.5). 



There is comparatively little difference between the temperatures at Fowey Eocks and Carysfort Eeef, these two 

 stations, located only 23 miles apart, being more closely related than are either of them to the Tortugas. The air 

 temperatures range slightly higher at this station than at Carysfort, but the surface curves correspond very closely 

 throughout each year, the greatest difference at any period being only 2° or 3°. The more prominent irregularities 

 in the surface curves at one station are almost invariably repeated in those of the other at the same period. The angles 

 indicating low temperatures for March, 1881, are more i>ronounced here than at Carysfort, but those for the last part 

 of 1882 are less marked. The maximum air and surface temperatures at this station are very nearly identical. 



Table showing the direction of the winds, by quadrants, for each month of the year, being the means of five years' observations. 



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