GEOGRAPHICAL RANGE OF THE CAMEL. 171 



turnal radiation under the clear sky of the 

 Libyan desert often reduces the temperature 

 to the freezing point. In latitude 25 N., Lyon 

 saw the thermometer fall to 26. The mercury 

 was below 32 several mornings in succession, 

 ice formed half an inch in thickness, and the 

 water-skins were frozen. In the autumn of 

 1850, it was so cold between Korasko and 

 Khartum on the Nile, that caravans were una- 

 ble to move for two or three days ; Denham and 

 Clapperton experienced hard frosts in latitude 

 13 N., but we do not learn that the camels of 

 the country were in any of these instances se- 

 riously injured by this severe weather. Other 

 breeds of the same species support far greater 

 degrees of cold without much apparent suffer- 

 ing. The one-humped camel abounds in con- 

 junction with the Bactrian throughout the 

 immediate basin of the Caspian and the Sea 

 of Azoff, and far to the east under the same 

 parallel. In this latitude the winters are of 

 great severity, and according to Fraser, travel- 

 lers sometimes perish of cold even in the vicin- 

 ity of Teheran. The Calmucks, who possess 

 great numbers of both species, spend their sum- 

 mers in higher latitudes, migrate in autumn to 

 the south of 50 N. L., 1 and pass the winter on 



1 This migration finds its counterpart in central Africa, 

 where the camel moves northwards from the highlands to 



