56 Professor Carpenter on the Mean Temperature, ^'c, 



hours, will belong to both the diurnal and nocturnal portions, 

 and will enter twice into the calculations, while the other two 

 observations will represent the maxima of the portions of the 

 twenty-four hours to which they respectively belong. 



If it is, as I suspect, then, that the results of observations 

 and calculations are, particularly in hot countries, frequently 

 too high, a little attention to the subjects above hinted at may 

 shew that there is really no difference between the mean tem- 

 perature of climates and of water derived from such depths as 

 not to be affected by the change of seasons. In my tables the 

 most exact agreement is shewn between these temperatures 

 at this place. The same appears to be the case in the island 

 of Cuba, notwithstanding that we find the following statement 

 in the table in which Professor Kupffer compares the annual 

 temperature of places with that of the earth : " Havana, tem- 

 perature of the earth, 74.30° ; of the air, 78.12°." Now, Ha- 

 vana and Matanzas are in the same latitude, or nearly so, and 

 there can be but little difference between the temperatures at 

 the two places. Mr A. Mallary, in this Journal, vol. xxxi. 

 p. 289, gives the annual temperature at Matanzas as 77.06°, 

 Fahrenheit, which he derives as a mean of the following aver- 

 ages of observations: Sunrise 7217°, 2 p.m. 81.41°, and sun- 

 set 77.61° Fahrenheit. Now, a mean of these observations 

 would unquestionably give a mean too high by more than a 

 degree, which would reduce the mean 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° Fahrenheit, thus affording a probability, at least, that 

 there also the mean temperatute of the air and of the earth, 

 at a certain depth, is the same. 



What inferences might not be drawn by travellers in this 

 country, particularly if they belonged to the anti-Huttonian 

 school of geologists l I will not go out of my own neighbour- 

 hood. The temperature of water taken from strata whose 

 average depth below the surface should be seventy or eighty 

 feet, would be found to have at Baton Rouge a temperature 



