EXPLANATION OP OCEAN TEMPERATURE CHART No. 5. 



MARTIN'S INDUSTRY LIGHT-SHIP, SOUTH CAROLINA. 

 Observer : John Masson. 



Position.— This lighfc-shLp is located off the entrance to Tort Royal Sound, Soutli Carolina, and about 390 miles 

 northerly from Fowey Rocks, Florida. It is anchored about Si miles from land, directly in front of Martin's Industiy 

 Shoal, from the outer edge of which it is distant a little more than a mile, the depths between ranging from 6J to 8 

 fathoms. The 10-fathom curTO is distant about 9 miles, the 20-fathom curVb about 3-2 hailes, and the 100-fathom 

 curve about 62 miles. 



Geographical position.— 1.3,titu.i&, 32° 05' (31") N. ; longitode, 80° 35' (07") W. 



Depth of water. — Nine fathoms. 



Sange of temperature,— Air, 41°.5 (45° to 86."5); surface, 38° (47° to 85°). 



The conditions influencing the temperature at Martin's Industry Shoal are very different from those prevailing 

 at the Florida Roef stations. The range of temperature is very much greater, and the temperature plottings on the 

 chart form much more pronounced curves. The surface curves, although more regular than those for the air, are 

 nearly parallel with them throughout each year, and the difference between the surface and air temperatures are 

 seldom great. Tbe maximum and minimum temperatures are nearly the same for both the air and surface, the lat- 

 ter having a slightly smaller range than the former. The maximum temperatures are about the same here as at 

 Fowey Rooks, and Carysfort Reef, but the minimums are over 20° lower. 



Tabic showing the dii'ection of the winds, by quadrants, for each month of the year, being the means office years' observatio'is. 



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