YELLOW FEVER. 121 



even at Cumaiia, Porto Cabello, or Core, the sea-breeze CHAP. XL 

 being less felt, and the temperature being increased by 

 the radiant caloric emitted by the rocks after sunset. 



The examination of the thermometrical observations, Thermome- 

 inade at La Guayra during nine months by Don Joseph yation's!''"^'' 

 Herrera, enabled Humboldt to compare the climate of 

 that port with those of Cumana, Havannah, and Vera 

 Cruz. The result of this comparison was, that the first 

 mentioned is one of the hottest places on the globe ; 

 that the quantity of heat which it receives in the course 

 of a year is a little greater than that experienced at 

 Cumana ; but that in November, December, and Jan- 

 uary, the atmosphere cools to a lower point. The mean 

 temperature of the year in these several districts is as 

 follows : — At La Guayra, nearly 82'6° ; at Cumana, 

 81-8° ; at Vera Cruz, 77-7° ; at Havannah, 78-1° ; while 

 at Rio Janeiro it is 74'3° ; at Santa Cruz in Teneriffe, 

 71-4° ; at Cairo, 72-3° ; and at Rome, 60-4°. 



At the time of Humboldt's visit to La Guayra, the Yeiiow 

 yellow fever, or calentura amarilla, had been known fever. 

 only two years there, and the mortality had not been 

 very great, as the confluence of strangers was less than 

 at Havannah and Vera Cruz. Some individuals, even 

 Creoles and mulattoes, were occasionally taken off by 

 remittent attacks, complicated with bilious symptoms 

 and hemorrhages, and their death often alarmed un- 

 seasoned Europeans ; but the disease was not propagated. 

 On the coast of Terra Finna this malignant typhus was 

 known only at Porto Cabello, Carthagena, and Santa 

 Martha. But since 1797 things have changed. The ^^^ esoftiie 

 extension of commerce having caused an influx of distemper. 

 Europeans and seamen from the United States, the 

 distemper in question soon appeared. It is maintained 

 by some, that it was introduced by a brig from Phila- 

 delphia ; while others think it took its birth in the 

 country itself, and attribute its origin to a change in 

 the constitution of the atmosphere caused by the over- 

 flowings of the Rio de la Guayra, which inundated the 

 town. This fever has since continued its ravages, and 



