284 The Andes and the Amazon. 



head waters of the Napo ; the Indians use it instead of 

 flint (which does not occur there) in striking a light. Dar- 

 win found silicified trees on the same slope of the Andes 

 at the Uspallata Pass. 



The climatology of the Valley of the Amazon is as sim- 

 ple as its physical geography. There is no circle of the 

 seasons as with us — nature moves in a straight line. Tlie 

 daily order of the weather is uniform for months. There 

 is very little difference between the dry and hot seasons ; 

 the former, lasting from July to December, is varied with 

 showers, and the latter, from January to June, with sunny 

 days, while the daily temperature is the same within two or 

 three degrees throughout the year. On the water-shed be- 

 tween the Orinoco and Negro it rains throughout the year, 

 but most water falls between May and November, the cool- 

 est season in that region. On the Middle Negro the wet 

 season extends fi-om June 1st to December 1st, and is the 

 most sultry time. 



Comparatively few insects, birds, or beasts are to be seen 

 in summer ; but it is the harvest-time of the inhabitants, 

 who spend the glorious weather rambling over the plaias 

 and beaches, fishing and turtle-hunting. The middle of Sep- 

 tember is the midsummer of the valley. The rainy season, 

 or winter, is ushered in by violent thunder-storms from the 

 west. It is then that the woods are eloquent with buzzing 

 insects, shrill cicadas, screaming parrots, chattering monkeys, 

 and roaring jaguars. The greatest activity of animal and 

 vegetable life is in June and July. The heaviest rains fall 

 in April, May, and June. Scarcely ever is there a continu- 

 ous rain for twenty-four hours. Castelnau witnessed at 

 Pebas a fall of not less than thirty inches in a single storm. 

 The greatest amount noticed in New York during the whole 

 month of September was 12.2 inches. The humidity of 

 the atmosphere, as likewise the luxuriance of vegetation and 



