THE VOYAGE OF THE BEAGLE 



395 



in the broken state of the craters, composed of the soft and 

 yielding tuff, is easily explained. 



Considering that these islands are placed directly under 

 the equator, the climate is far from being excessively hot; 

 this seems chiefly caused by the singularly low temperature 

 of the surrounding water, brought here by the great south- 



Culpepper I r 



cm Polar current. Excepting during one short season, very 

 little rain falls, and even then it is irregular ; but the clouds 

 generally hang low. Hence, whilst the lower parts of the 

 islands are very sterile, the upper parts, at a height of a 

 thousand feet and upwards, possess a damp climate and a 

 tolerably luxuriant vegetation. This is especially the case 

 on the windward sides of the islands, which first receive and 

 condense the moisture from the atmosphere. 



In the morning (17th) we landed on Chatham Island, 

 which, like the others, rises with a tame and rounded out- 

 line, broken here and there by scattered hillocks, the remains 



9 



Wenman I 



eOMiles. 



Jtirboroughr 



