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find any tribes resembling some of the nations of Africa in the deep jet of their colour, it proceeds from the mild temperature of the tropical zone in America.  Mexico, which forms the northern por-tion of that zone, consists chiefly of a narrow neck of land dividing the Atlantic from the Pacific ocean, and every where rising into high hills.  As you proceed to the South immediately below the isthmus of Darien, Terra Firma, on one side, presents an Alpine bed of lofty mountains.  On the other side runs the chain of the Andes, with its elevated sum-mits covered with snow.  On the West of these lies the narrow empire of Peru, constantly refreshed by temperate winds from the Pacific ocean, and over-shadowed by a canopy of dense vapour which pre-vents the rays of the sun penetrating with great force to the earth.  On the East is spread out the im-mense country of Amazonia flooded during a great portion of the year by the waters of the Maragnon, and its tributary rivers, and covered with thick and dark forests, beneath which grows a luxuriant tissue of vines and weeds which can hardly be penetrated by the traveller, and utterly excludes the sun.  Here are no arid deserts of sand; and from such a rich vegetable growth arises a refrigerating perspiration

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which, together with the vapour of so many streams, united with the effluvia of the moist and shaded earth that cannot be wholly absorbed even by the thick vegetation on its surface, produces an uncom-mon coolness in the atmosphere.*  This moderate temperature is increased by the East wind which perpetually follows the course of the sun through the equatorial regions.  Having deposited in the Atlantic ocean the excessive heats acquired in its passage across the continent of Africa it regains a tempera-ture comparatively mild before it arrives at the American coast; whence it continues its course over thick forests and flooded lands, till it meets the cold ranges of the Andes.  The lofty and spreading for-ests of tropical America are at once a proof of the temperature of the atmosphere, and contribute to

* Dr. Robertson quotes two eminent naturalists, Piso and Margrave, who had resided long in Brazil, who represent the climate as being very temperature and mild compared with that of Africa.  The air, they say, is not only cool, but chilly through the night, insomuch that the natives kindle fires every even-ing in their huts.  This is confirmed by different writers con-concerning various countries within that vast region, viz. Neuhoff concerning Brazil; Gumilla concerning the countries on the Oronoco; Acugna concerning those along the Amazon; and Biet in his voyage de la France Equinox. gives a similar ac-count of Cayenne-Hist. Amer. Note 5th, vol. 2d.