Il6 PHILOSOPHICAL TRANSACTIONS. [ANNO 1781. 



The rendezvous appointed for the fleet being off Cape Fear, their course, on 

 approaching the American coast, became north-westward. On the '23d of 

 April the heat of the sea was 74°, the latitude at noon '28° 7' n. Next day the 

 heat was only 71°, then in latitude 29 12'; the heat of the water, therefore, 

 was now lessening very fast in proportion to the change of latitude. The 25th 

 the latitude was 31° 3'; but though they had thus gone almost 2° farther to the 

 northward, the heat of the sea was this day rather increased, it being 72° in the 

 morning, and 72% in the evening. Next day, the 26th of April, at half after 

 8 in the morning, the thermometer rose to 78°; higher than he had ever ob- 

 served it, even within the tropic. As the difference was too great to be imputed 

 to any accidental variation, Dr. B. immediately conceived that they must have 

 come into the gulf-stream, the water of which still retained great part of the 

 heat that it had acquired in the torrid zone. This idea was confirmed by the 

 subsequent regular and quick diminution of the heat : the ship's run for a quarter 

 of an hour had lessened it 2° ; the thermometer at 8A h being raised by sea- 

 water fresh drawn only to 7 6° ; by 9 the heat was reduced to 73°, and in J- of an 

 hour more, to 7 1° nearly : all this time the wind blew fresh, and they were going 

 7 knots an hour on a north-western course. The water now began to lose the 

 fine transparent blue colour of the ocean, and to assume something of a greenish 

 olive tinge, a well-known indication of soundings. Accordingly, between 4 and 

 5 in the afternoon ground was struck with the lead at the depth of 80 fathoms, 

 the heat of the sea being then reduced to 6g°. In the course of the following 

 night and next day, as they came into shallower water and nearer the land, the 

 temperature of the sea gradually sunk to 65°, which was nearly that of the air 

 at the time. 



Bad weather on the 26th prevented them from taking an observation of the 

 sun ; but on the 27th, though it was then cloudy at noon, they calculated the lati- 

 tude from 2 altitudes, and found it to be 33° 2& n. The difference of this 

 latitude from that which was observed-on the 25th, being 2° 23', was so much 

 greater than could be deduced from the ship's run marked in the log-book, as to 

 convince the seamen that they had been set many miles to the northward by the 

 current. 



From these observations, Dr. B. thinks it may be concluded, that the gulf- 

 stream, about the 33d degree of north latitude, and the 76th degree of longi- 

 tude west of Greenwich, is, in the month of April, at least () degrees hotter 

 than the water of the sea through which it runs. As the heat of the sea-water 

 evidently began to increase in the evening of the 25th, and as the observations 

 show that they were getting out of the current when he first tried the heat in 

 the morning of the 26th, it is most probable that the ship's run during the night 

 is nearly the breadth of the stream measured obliquely across ; that, as it blew a 



