On the Methods of obtaining Mean Temperatures. 53 



ing that we find the following statement in the table in which 

 Prof. Kupffer compares the annual temperatures of places with 

 that of the earth : " Havana, temperature of the earth, 74.30° ; 

 of the air, 78.12°." Now Havana and Matanzas are in the same 

 latitude, or nearly so, and there can be but little difference be- 

 tween the temperatures at the two places. Mr. A. Mallory, in 

 this Journal, "Vol. xxxi, p. 289, gives the annual temperature at 

 Matanzas as 77.06° Fahr., which he derives as a mean of the fol- 

 lowing averages of observations: sunrise 72.17°, 2 p. m. 81.41°, 

 and sunset 77.61° Fahr. Now a mean of these observations 

 would unquestionably give a mean too high by more than a de- 

 gree, which would reduce the mean down to about 76°. My 

 friend Mr. W. H. Potter has been kind enough to examine the 

 temperature of wells, &c. for me, during a residence of a year in 

 that island, particularly near Cardanus, in the same latitude and 

 near Matanzas, and the observations frequently repeated through 

 the year ; and the temperature, apparently invariable, was 76° 

 Fahr., thus affording a probability at least, that there also the 

 mean temperature of the air, and of the earth at a certain depth, 

 is the same. 



What inferences might not be drawn by travellers in this coun- 

 try, particularly if they belonged to the anti-Huttonian school of 

 geologists? I will not go out of my own neighborhood. The 

 temperature of water taken from strata whose average depth be- 

 low the surface should be seventy or eighty feet, would be found 

 to have at Baton Rouge a temperature of about 64.50° Fahr. 

 But we are informed by the tables of the Army Meteorological 

 Register, that the annual mean for that place is 68.07°, making 

 a difference of 3.57°. Now we cannot mistrust the accuracy 

 with which the observations were noted in this case, nor the cor- 

 rectness with which the calculations were made, but there can 

 be no doubt that too high a temperature has been obtained for 

 want of attention to things generally considered as of minor im- 

 portance, and in consequence of the too general adoption of 

 methods which have been found to give correct results in other 

 climates. 



Jackson, La., May 9, 1842. 



