230 NOTES OF A NATURALIST. 



latter region the sky is generally clear in summer, 

 and that the surface is exposed to the direct rays of 

 a sun not far from vertical, while on the southern 

 coast the sun is constantly veiled by heavy clouds, it 

 is obvious that all the conditions are present that must 

 depress the snow-line to an exceptional extent, and 

 allow of those accumulations of snow that give birth 

 to glaciers. When a comparison is drawn between 

 South Chili and Norway, it must not be forgotten 

 that at Bergen, where the Norwegian rainfall is said 

 to be at its maximum, the annual amount is sixty- 

 seven inches, or exactly one-half of that registered in 

 Chiloe. 



It is a confirmation of this view of the subject that 

 in going southward from the parallel of 42° to Cape 

 Froward in the Straits of Magellan, through 12° of 

 latitude, while the fall of mean yearly temperature 

 must be reckoned at 8° Fahr., the depression of the 

 snow-line cannot exceed three thousand feet* Of 

 course, we have no direct observations of rainfall in 

 the Channels or on the west side of the Straits of 

 Magellan, but there is no doubt that it diminishes 

 considerably in going southward. 



To the south of Eyre Sound the main channel 

 opens to a width of four or five miles, and is little 

 encumbered by rocky islets, so that we kept a direct 

 course a little west of south, and in less than two 

 hours reached the southern extremity of Wellington 

 Island, and gained a view of the open sea through a 



* The estimates given by Pissis do not rest on accurate observations, 

 and seem to me exaggerated. I should be inclined to reckon the 

 difference of height of the snow-line between the extreme stations as 

 nearer to two thousand than to three thousand feet. 



