XXXI.-TEMPERATURES IN THE GULF OF MEXICO. 



[For the following article on the temperatures and depths of the Gulf 

 of Mexico, with reference to the abode therein of shad and salmon, I am 

 indebted to Capt. C. P. Patterson, Superintendent of the United States 

 Coast-Survey. It is probable that the earlier observations do not give 

 a sufficiently low indication of the temperature; all indications prior 

 to the introduction of the encased-bulb thermometers of Negretti and 

 Miller being liable to this error. — S. F. Baird.] 



United States Coast- Survey report for ISoi, p. 72. — " Between latitude 

 28° to 2QO 40', and within 30' of longitude of Pass a Loutre, (the latitude 

 of the entrance of the pass being 29° 10',) the temperature of the water 

 at the surface was found to be from 77° to 78° Fahrenheit, the air being 

 from 72° to 77°. At 30 fathoms, within the same limits, the temper- 

 ature was about 77°, but the subsurface temperatures were very irreg- 

 ular. These observations were made on the 5th, 6th, and 7th of Aj)ril, 

 1854. North of latitude 28° 40', 1° east of Pass a Loutre, the temper- 

 atures at the surface were 70°, 69°, and 68° on the 8th and 9th of April, 

 the air being 71° and 70°, and the temperature at 15 fathoms 70°.5 and 

 68°, showing, within forty nautical miles, a fall in the temperature of 

 the surface and below of some 8° Fahrenheit. This remarkable change 

 requires further investigation." — (From the Hydrographic Work of Lieu- 

 tenant Sands relating to Deep-Sea Soundings and Temperatures.) 



United States Coast- Survey report for 1855, p. 89. — " Late in December, 

 while the temperature of the air was from 61° to 73°, surface temper- 

 atures in the Gulf were found as high as 77° Fahrenheit, and that at 

 the depth of about 230 fathoms the lowest temperature measured was 

 50° Fahrenheit." — (Reported by Lieutenant-Commander Sands.) Sev- 

 eral stations off the mouth of the Mississippi, at depths from 15 to 50 

 fathoms, as given on his sketch, make the surface and subsurface tem- 

 peratures nearly the same, but some stations were warmer than others, 

 varying from 68° to 78°. 



United States Coast-Survey report for 1856, p. 75. — (From Commander 

 Sands' work. He ran lines of soundings between Key West and the 

 Mississippi Delta, &c.) — "The interesting results as to the deep-sea tem- 

 peratures developed along this line are shown in the diagram of sketch 

 No. 40. Between latitudes 27° 06' and 28° north and longitudes 85° 20^ 

 and 86° 39' west, in the Gulf, at the depths of 421, 610, and 790 fathoms, 

 temperatures as low as 35° and 36° Fahrenheit were reached in the 

 mouth of April. The lowest temperature in winter belonging to this 

 region is about 52°, at a depth of 230 fathoms." 



