BOOK V. 
GEOGRAPHY. 
489 
Rio Janeiro, in latitude 20° 59^ S., is as low as 74.3° ; and at 
the Havannah, in nearly the same parallel in the northern 
hemisphere, it ranges between 77° and 77.9°. The whole of 
the western coast of South America, as far as the sands of 
Peru, in latitude 10° and 14° S ., are affected so much by the 
continual prevalence of clouds and the low temperature (59.9°) 
of the currents setting round Cape Horn, that the mean tem- 
perature of the year in those parts does not exceed 68° or 69°. 
Hence the plants of Lower Peru live in a temperature not ex- 
ceeding, by day, 68° or 72°, and by night 59° or 62°. Near 
the coast Humboldt observed the thermometer as low as even 
55.4° in 12° 2^ S* lat. With this exception, there is httle dif- 
ference in the temperature of the southern hemisphere as low 
as 34° S. lat., either in New Holland, Africa, or America. 
The mean temperature of Port Jackson, in 33° 51' S. lat., has 
been ascertained to be 66.6° ; of the Cape of Good Hope, in 
33° 55' S. lat., to be 66.8° ; and of Buenos Ayres, in 34° 36' 
S. lat., to be 67.6°. In the northern hemisphere the mean 
temperature, in latitude 34°, is 67.8°. It is extremely pro- 
bable that, as far as the parallel of 57° S. lat., the differences 
in the temperature of the two hemispheres are greater in the 
summer than the winter. The cold of the Falkland Islands, 
in latitude 51J° S., is less than that of London in the same 
latitude to the north. The arborescent ferns and epiphytal 
Orchideae are often injured by the cold in Van Diemen's 
Island, latitude 42° S. ; and in the southern part of New 
Zealand, latitude 46° S., Cook observed, in latitude 43°- 
44° S., in July in the middle of winter, that the thermometer 
at noon was usually between 46 ^ and 51°. At Rome, latitude 
41° 53' N., the thermometer at noon in January rarely reaches 
51° — 53°: in Paris the mean noon-day temperature of January 
is, according to Arago, 38.7°. For this reason it is supposed 
that the climate of the southern hemisphere does not differ 
from that of the north so much in the greater coldness of the 
winters as of the summers. According to Humboldt, the 
greatest heat in the parallels of 48° and 58° of S. lat. does 
not exceed 43.7° — 46.8° ; while at St. Petersburg!! and Umea, 
in 59° 66' and 63° 50' N. lat., it is 65.2° and 62.6°. In the 
Straits of Magellan, between 53° and 54°. S. lat., snow falls 
