EXPLANATION OP OCEAN TEMPERATURE CHART No. 27. 



Isothermal lines connecting the Beries of light-house stations on the eastern coast of the United States represented 

 on Chart No. 1, constructed for every 5° of temperature, Fahrenheit, from 40° to 80°, inclusive, for the year 18S2. 



The isotherm of 40° extends south continuously in the spring only as far as Absecon Inlet ; during the period of 

 falling temperature, however, the isotherm of that value extends to Body's Islauil. Higher temperatures than .55^ 

 were recorded at Petit Manan, from August 18 to November 8, hut the isotherms of 55° begin at Seguin Island. The 

 isotherm of 00° appeared at Boon Island and Thatcher's Island, but not elsewhere north of Vineyard Sound, although 

 the record is incomplete for Nantucket New South Shoal. The isotherms of 65° extend north continuously to Vineyard 

 Sound, and the same temperature was also recorded at Thatcher's Island. At the Tortngas, the temperature was 

 below 75° between May 9 and 21, and below 80° between October 8 and 14. 



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