488 
GEOGRAPHY. 
BOOK V. 
on the west than on the east side of the range. It is probable, 
however, that this difference does not extend higher up than 
Lake Erie, in 42° N. lat. ; for, both beyond Lake Superior 
and Hudson's Bay, the earth is said to be constantly frozen at 
three feet from the surface ; a phenomenon which also occurs 
in Siberia, about the river Lena, in about 62° N. lat., near 
the town of Jakutsk ; while, in Lapland, in 70° near Vadsoe, 
the temperature of the earth is found to be as much as 3° 
or 4° above the freezing point ; whence it appears that the 
climate of the north of Europe is warmer than that of the 
same latitudes in Asia and America. We therefore shall not 
be far away, if we conclude that the isothermal lines bend 
towards the tropics in Europe, and towards the poles in Tar- 
tary and America. 
As we approach the equator there appears to be little differ- 
ence in the mean temperature of the year, either in the new 
or old world. 
Of the Old World. 
The mean temperature of Senegal is 79.7° in lat. 24° 30' N. 
of Madras is 80.4° in lat. 13° 5' N. 
of Batavia is 77.4° in lat. 6° 10^ S. 
of Manilla is 78.0° in lat. 15° N. 
Of the New World. 
The mean temperature of Cumana is 81.6° in lat. 10° 27' N. 
of the Antilles is 81.6° in lat. 15° N. 
of Vera Cruz is 78.0° in lat. 19° 12' N. 
of Havannah is 78.0° in lat. 23° 12' N. 
It is probable, however, that the summers of Asia are more 
fervid than those of America ; for, according to Roxburgh, 
the mean temperature of Madras, in latitude 13° 5' N., in the 
month of July, is 89.4° ; while that of Cumana, in latitude 
10° 27', does not exceed 84.4°. 
To the south of the equator, the temperature of the east 
seems to be higher than that of corresponding latitudes in 
the west: thus, the mean temperature of the Mauritius, in 
20° 9' S. lat., has been ascertained to be 80.4° ; while that of 
