54 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



48°. 5 ; at the former for April, 45°.6, 50°, 54o.5, So^.T ; for November, 

 540.2, 520.1, 50O, 470. At Norfolk the averages for the last half of 

 March are 48° aud 50°. 



The movements of the menhaden in other waters have not been very 

 carefully observed, bat we know that they enter the Potomac late in March 

 aud early in April, and that they linger till the last part of November. 



In 1874 the young menhaden lingered in the Lower Potomac until the 

 middle of December. In 1876 the average for December surface tem- 

 perature at Norfolk was 30^.8, for bottom temperature 30^.4. In 1874 

 the surface average for December at Norfolk was 43°, or 6°.4 higher than 

 in 187G, the year from which our tables of observations are made up. The 

 average for Norfolk surface temperature in November was, in 1870, 53^.4, 

 in 1874, 550.1 or lo.7 higher. It is quite probable that in 1874 the water 

 of the Lower Potomac did not become colder than 50° until December. 



At Wilmington the monthly means of bottom temperature in 1876 

 and 1877 were for December, 43^.1, January, 43°, February, 48^.5 ; in 

 1874 and 1875, December, 48^.1, January, 43o.8, February, 45o.5. De- 

 cember, 1876, was uuusnally cold, the mean temperature of the air 

 being 4Go.3, against oO^.i for the same mouth in 1874. January and 

 February of 1874 were relatively cold, their air temperature being 48o.l 

 and 530.1, against 57o.l and 52o.5 in 1870. The surface quarter-mouth 

 averages for the last half of February, 1877, are 49o.l, 50O.5 ; for the first 

 half of March, 1870, 52o.6, 57o ; for late November and early December, 

 1870, 570.1, 5306, 460.6, 450.3. 



No observations have been made upon the movements of the menhaden 

 at Wilmiiigtou. At Beaufort, 30 miles farther north, they appear to be 

 absent during the winter. , 



It is much to be regretted that there are no temperature observations 

 from Cape Hatteras. The relations of this locality to the Gulf Stream 

 are peculiar, and corresponding peculiarities in the temperatures no 

 doubt exist. The hundred fathom curve is distant about 40 miles from 

 the point of the cape, and the average summer limits of the Gulf Stream, 

 as laid down upon the British Admiralty charts, extend nearly into this 

 curve. The observations made at Wilmington, situated as it is in a 

 bend of the coast, at least 100 miles from the summer limits of the Gulf 

 Stream, and at the mouth of a river which rises 200 miles away in the 

 elevated central portion of North Carolina, can hardly be taken as 

 criteria of the temperatures of Cape Hatteras. This is still more unfor- 

 tunate from the fact that tl»e movements of the menhaden, bluefish, 

 "seatrout," and other warm-water species are very peculiar at this 

 point. It will be strauge if the monthly mean of water temperature for 

 Cape Hatteras in December, and perhaps January, does not prove to be 

 more than 50-. 



Savannah is at least 120 miles from the Gulf Stream, and its means 

 for December and January, 1870-1877, as well as those of Charleston, 

 are below 50o. Charleston water appears to be uniformly warmest. In 



