M. Humboldt on Isothermal Lines . 29 
mean temperature of the ambient air. The temperature of the 
interior of the earth is, at 
Temp. 
Temp. 
Lat. 
Fahr, 
Lat. 
Fahr. 
Vadso, 
70°. 0 
35°. 96 
Paris, 
48° 50' 
53 ,°6 
Berlin, 
52.31 
49.28 
Cairo, 
30 2 
72 .5 
In equinoctial America, I have found it in the plains from 
7 7° to 78°. 8. 
The following are examples of the decrease of temperature 
from the plains to the tops of mountains. 
Alt. in 
Temp. 
Feet. 
Fahr. 
Spring of Utliberg, near Zurich, 
1532 
48°. 92 
Ditto of Rossbaden at St Gothard, 
7016 
38.30 
Between the Tropics I have found, 
Alt. in 
Temp. 
Feet. 
Fahr. 
Springs of Cumanacoa, 
1,148 
72°. 5 
Ditto Montserrate, above Santa Fe de Bogota, 
10,680 
59.9 
Ditto in the Mine of Hualgayoc in Peru, 
11,759 
53.24 
In the plains, and to the height of 3280 feet, between the pa- 
rallels of from 40° to 45°, the mean temperature of the earth is 
nearly equal to that of the ambient air ; but very accurate ob- 
servations by Baron Yon Buch and Wahlenberg tend to prove, 
that in high latitudes, towards the top of the Swiss Alps, for 
example, beyond the height of 1400 or 1500 metres (4592 or 
4920 feet), the springs and the earth are 5°.4 warmer than the 
air. 
Mean Temp. 
Temp, of the 
of Air, 
Interior of 
Zone of 30°— 55°. 
Lat. 
Fahr. 
the Earth. 
Cairo, 
30° 
72°.6S 
72°. 50 
Natchez, 
31 28 
64.76 
64.94 
Charlestown, 
33 0 
63.14 
63.50 
Philadelphia, 
39 56 
53.42 
52.16 
Geneva, ... 
46 12 
49.28 
50,74 
Dublin, - 
53 21 
49.10 
49.28 
Berlin, - 
52 31 
47.30 
49.28 
Kendal, 
54 17 
46.22 
47.84 
Keswick, 
54 33 
48.02 
48.56 
Zone of 55°— -70°, 
Carlscrona, 
56 6 
46.04 
47.30 
Upsal, 
59 51 
41.90 
43.70 
Umeo, 
63 50 
33.26 
37.22 
Vadso, 
o 
o 
29.66 
35.96 
