39° PERU CHAP. 



by the drainage of some little pools. Miasma is not always 

 produced by a luxuriant vegetation \\'ith an ardent climate ; 

 for many parts of Brazil, even where there are marshes and a 

 rank vegetation, are much more healthy than this sterile coast 

 of Peru. The densest forests in a temperate climate, as in 

 Chiloe, do not seem in the slightest degree to affect the healthy 

 condition of the atmosphere. 



The island of St. Jago, at the Cape de Verds, offers 

 another strongly-marked instance of a country, which any one 

 would have expected to find most healthy, being very much 

 the contrary. I have described the bare and open plains as 

 supporting, during a few weeks after the rainy season, a thin 

 vegetation, which directly withers away and dries up : at this 

 period the air appears to become quite poisonous ; both natives 

 and foreigners often being affected with violent fevers. On 

 the other hand, the Galapagos Archipelago, in the Pacific, with 

 a similar soil, and periodically subject to the same process of 

 vegetation, is perfectly healthy. Humboldt has observed that 

 "under the torrid zone, the smallest marshes are the most 

 dangerous, being surrounded, as at Vera Cruz and Carthagena, 

 with an arid and sandy soil, which raises the temperature of 

 the ambient air." ' On the coast of Peru, however, the 

 temperature is not hot to any excessive degree ; and perhaps 

 in consequence the intermittent fevers are not of the most 

 malignant order. In all unhealthy countries the greatest risk 

 is run by sleeping on shore. Is this owing to the state of the 

 body during sleep, or to a greater abundance of miasma at 

 such times ? It appears certain that those who stay on board 

 a vessel, though anchored at only a short distance from the 

 coast, generally suffer less than those actually on shore. On 

 the other hand, I have heard of one remarkable case where a 

 fever broke out among the crew of a man-of-war some hundred 

 miles off the coast of Africa, and at the very same time that 

 one of those fearful periods ^ of death commenced at Sierra 

 Leone. 



No State in South America, since the declaration of 



1 Political Essay on the Kingdom of New Spain, vol. iv. p. 199. 



2 A iimilar interesting case is recorded in tlie Madras Medical Quart. Journ. 

 1839, p. 340. Dr. Ferguson, in his admirable Paper (see 9th vol. o{ Edinlmrgh 

 Royal jyans.), shows clearly that the poison is generated in the drying process ; and 

 hence that dry hot countries are oflen the most unhealthy. 



