Vol. I] STEWART— BOTANY OF THE GALAPAGOS ISLANDS 227 



Table of Galapagos Temperatures, 1905-1906— Continued 



From this table it is seen that the warmest weather of the 

 year occurs in the months of February and March, and the 

 coldest during the months of July, August, and September. 

 There is no great amount of difference in the temperature of 

 the air morning and noon, 5° F. being about the average, 

 while the difference in the temperature of the water is even 

 less than this. The air is usually 1° to 3° warmer than the 

 water in the morning, except during the spring months, when 

 the opposite is the case. 



The uniformly low temperature for an equatorial region is 

 due to the coolness of the water which surrounds all but the 

 northernmost islands of the group. The Humboldt current, 

 which sweeps up from the antarctic regions along the west 

 coast of South America, turns outward at about the latitude 

 of these islands and bathes their shores with unusually cool 

 water for several months of the year. The water remains 

 cool until the sun reaches well south of the equator, in the 

 autumn and winter months, when it begins to become warmer 

 until it reaches its highest temperature in February and March. 

 After the sun passes the equator on its way north, the water 

 rapidly becomes cooler, the colder water seeming about to keep 



