VOYAGE FROM NEW YORK TO RIO DE JANEIRO. 19 



reference to latitude must have been attended by a corre- 

 sponding change of climate with reference to altitude. 

 Three degrees of temperature correspond to about one 

 thousand feet of altitude. If, therefore, it is found that 

 the ancient limit of glacier action descends on the Andes, 

 for instance, to 7,000 feet above the level of the sea under 

 the equator, the present line of perpetual snow being at 

 15,000, it is safe to infer that in those days the climate 

 was some 24 or thereabouts below its present temperature. 

 That is, the temperature of the present snow line then pre- 

 vailed at a height of 7,000 feet above the sea level, as the 

 present average temperature of Greenland then prevailed in 

 latitude 36. I am as confident that we shall find these 

 indications at about the limit I have pointed out as if I had 

 already seen them. I would even venture to prophesy that 

 the first moraines in the valley of the Maranon should be 

 found where it bends eastward above Jaen."* 



Although the weather is fine, the motion of the ship 

 continues to be so great that those of us who have not what 

 are popularly called " sea-legs," have much ado to keep our 

 balance. For my own part, I am beginning to feel a personal 

 animosity to " the trades." I had imagined them to be soft, 

 genial breezes wafting us gently southward ; instead of 

 which they blow dead ahead all the time, and give us no 

 rest night or day. And yet we are very unreasonable to 

 grumble ; for never were greater comforts and conveniences 



* It proved in the sequel unnecessary to seek the glacial phenomena of 

 tropical South America in its highest mountains. In Brazil the moraines are 

 as distinct and as well preserved in some of the coast ranges on the Atlantic 

 side, not more than twelve or fifteen hundred feet high, as in any glaciated 

 localities known to geologists in more northern parts of the world. The 

 snow line, even in those latitudes, then descended so low that masses of ice 

 formed above its level actually forced their way down to the sea-coast L A. 



