156 bulletin: museum of comparative zoology. 



Low temperature (55° to 56°), characterized the surface waters very 

 generally as Nantucket Shoals were crossed, though with occasional 

 readings of 60° or 61°, irregularities associated with the violent tidal 

 currents of that region. But when the deeper water to the south was 

 reached the temperature rose to 65° and higher. The coldest surface 

 water west or southwest of Nantucket was just off New York (62°- 

 63°) the warmest off the mouth of Chesapeake Bay (79°-80°) . And in 

 a general way we found a rise of temperature over the continental 

 shelf from north to south (Fig. 1). Thus it was 64°-67° between 

 Nantucket Shoals and the edge of the continental shelf, rising to 69° 

 and 70° abreast of Long Island, 70 miles off shore. Near New York, 

 however, it was much colder, as pointed out above; though it rose 

 again to 66° and 67° off Barnegat. Off shore on the line from Barnegat 

 to the Gulf Stream, the surface temperature rose to 74° at Station 

 10071. Off Delaware Bay it was 75°; 76° close in shore off Cape 

 Charles, and 78° off the mouth of the Chesapeake. In general, on 

 the several lines across the continental shelf, the surface water was 

 slightly warmest at the off shore station, i. e., nearest the Gulf Stream, 

 as shown in the following table: — 



Line C. 



Line D. 



but this was reversed off Chesapeake Bay (Line D), where the off shore 

 station was 76°, the in shore one 78°. Short though the stay in the 

 Chesapeake was, it was long enough for a decided warming of the 

 sui'face water to take place. On July 29, the surface temperature of 

 the Bay had risen 2° to 80°, and as we sailed northward, a consider- 

 ably greater discrepancy between our two sets of readings was noted. 

 Thus when the northerly line approached our previous course, south 

 of Cape Henlopen, the temperature had risen from 75° to 78°: off 

 Barnegat from 66° to 75°; and off Fire Island light-ship, where the 

 lines cross, the surface had warmed 4°, (69° to 73°) during the two 

 weeks interval. Since the salinity showed that no shoreward move- 

 ment of the surface waters of the Gulf Stream had taken place, this 

 rise of surface temperature was no doubt the result of solar warming. 



