EXPLANATION OF OCEAN TEMPERATURE CHART No. 5. 



MARTIN'S INDUSTRY LIGHT-SHIP, SOUTH CAROLINA. 



Observer : John Masson. 



PosifJoif.— This light-ship is located off the entrance to Port Royal Sound, South Carolina, and about 390 miles 

 northerly from Fowey Rocks, Florida. It is anchored about 8J miles from laud, directly in front of Martin's Industi-y 

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

 fathoms. The 10-fathom curve is distant about 9 miles, the 20-fatliom curve about 32 miles, and the 100-fathom 

 curve about 02 miles. 



Geogmjyhicaliiosilion.— 'Latitude, 33° 05' (31") N. ; longi(«udo, 80° 35' (07") W. 



Depth of water. — Nine fathoms. 



Sange of temperature.— Mr, 41°.5 (45° to 8G."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 Reef 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. The maximum and minimum temperatures are nearly the same for both the air aud surface, the lat- 

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

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



Table showing the direction of the teinds, bij quadrants, for each month of the year, being the means of five years' obscrvatio'is. 



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