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 



Mr. W 



id 



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 



d 



climates. 



Jackson, La., May 9, 1842. 



