THE VOYAGE OF THE BEAGLE 387 



seem in the slightest degree to affect the healthy condition 

 of the atmosphere. 



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

 other 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 na- 

 tives and foreigners often being affected with violent fevers. 

 On the other hand, the Galapagos Archipelago, in the Pa- 

 cific, 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." 6 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 rnan-of-war some hundred miles off the coast of Africa, 

 and at the same time one of those fearful periods' of death 

 commenced at Sierra Leone. 



No state in South America, since the declaration of inde- 

 pendence, has suffered more from anarchy than Peru. At 

 the time of our visit, there were four chiefs in arms con- 

 tending for supremacy in the government: if one succeeded 

 in becoming for a time very powerful, the others coalesced 

 against him; but no sooner were they victorious, than they 



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



8 A similar interesting case is recorded in the Madras Medical Quart. 

 Tourn., 1839, p. 340. Dr. Ferguson, in his admirable Paper (see 9th vol. of 

 Edinburgh Royal Trans.), shows clearly that the poison is generated in 

 the drying process; and hence that dry hot countries are often the most 

 unhealthy. 



