EXPLANATION OP OCEAN TEMPERATURE CHART No. 21. 



BOON ISLAND LIGHT-HOUSE, MAINE. 



Olserver: Alfred J. Leavitt. 



Location of station. — Boon Island is a small, low, rooky island, off York Harbor, Maine, and 5i miles from Cape 

 Neddick, the nearest part of the maialauil. From Thatcher's Island it is distant about 35 miles, in a northerly direc- 

 tion. Within a radius of 1 mile depths of 5^ to 25 fathoms occur, and a depth of 60 fathoms is reached at a distance 

 of about 6i miles to the eastward and southeastward. 



Geographical position of the light-house.— LutitnAe, 43° 07' 17" N. ; longitude, 70° 28' 37" W. 



Depth of water. — ^Nine fathoms. 



Sange of temperature (March 1 to Jauuary 1).— Air, 51° (22°.o to 73°.5) ; surface, 29° (83° to 62°). 



This station affords the highest maximum surface temperature of any of the stations located in the northern part 

 of the Gulf of Maine. This maximum is 5° lower than at Thatcher's Island, but agrees exactly with the surface maxi- 

 mums at Pollock Eip and Nantucket New South Shoal. The maximum for the air is, however, somewhat higher at 

 Boon Island than at the two light-ships mentioned. The surface curves are more irregular than at the other stations 

 in the Gulf of Maine. It is necessary to explain, however, that the surface observations were not taken with any regu- 

 larity at this station, omissions of several days, sometimes as many as five or six days, occurring in a majority of the 

 ten-day periods. The omissions are much less frequent during the summer than the winter months. It is impossible 

 to calculate to what extent the results may be vitiated by this fact. 



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



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