A historical example of an idea that is now recognised as an alternative conception but was once treated seriously by scientists:
"Miasms are formed in the valley of Cariaco, as in the Campagna of Rome; but the hot climate of the tropics increases their deleterious energy. These miasms are probably ternary or quaternary combinations of azote, phosphorus, hydrogen, carbon, and sulphur.
The situation of the lagoon of Campoma renders the north-west wind, which blows frequently after sunset, very pernicious to the inhabitants of the little town of Cariaco. Its influence can be the less doubted, as intermitting fevers are observed to degenerate into typhoid fevers, in proportion as we approach the lagoon, which is the principal focus of putrid miasms. …These intermittent fevers assume a dangerous character, when persons, debilitated by long labour and copious perspiration, expose themselves to the fine rains, which frequently fall as evening advances. …What is remarkable enough, is the belief which prevails here as in the Campagna of Rome, that the air has become progressively more vitiated in proportion as a greater number of acres have been cultivated. The miasms exhaled from these plains have, however, nothing in common with those which arise from a forest when the trees are cut down, and the sun heats a thick layer of dead leaves. Near Cariaco the country is but thinly wooded. Can it be supposed that the mould, fresh stirred and moistened by rains, alters and vitiates the atmosphere more than the thick wood of plants which covers an uncultivated soil? To local causes are joined other causes less problematic. The neighbouring shores of the sea are covered with mangroves, avicennias, and other shrubs with astringent bark. All the inhabitants of the tropics are aware of the noxious exhalations of these plants; and they dread them the more, as their roots and stocks are not always under water, but alternately wetted and exposed to the heat of the sun. The mangroves produce miasms, because they contain vegeto-animal matter combined with tannin…
The unhealthiness of Cartagena comes form the great marshes surrounding the town on the east and north…Frightened about being exposed too long to the unhealthy Cartagena airs we moved on the Indian village of Turbaco…"
Alexander von Humboldt & Aimé Bonpland.(1907) Humboldt's Personal Narrative (Volume 1) (Thomasina Ross, Ed. & transl., 2012) Project Gutenberg eBook
