I have been in some measure drawn into this digression, by the consideration of the fine weather we experienced on the coast of Peru, even under the equinoctial, but I have not yet described the particularities of this weather.  I shall now therefore observe, that every circumstance concurred, in this climate, that could render the open air and the day-light desirable:  For, in other countries, the scorching heat of the sun in summer renders the greater part of the day unapt either for labour or amusement, and the frequent rains are not less troublesome in the more temperate parts of the year:  But, in this happy climate, the sun rarely appears.  Not that the heavens have at any time a dark or gloomy aspect; for there is constantly a cheerful gray sky, just sufficient to screen the sun, and to mitigate the violence of its perpendicular rays, without obscuring the air, or tinging the light of day with an unpleasant or melancholy hue.  By this means, all parts of the day are proper for labour or exercise in the open air; nor is there wanting that refreshing and pleasing refrigeration of the air which is sometimes produced by rains in other climates; for here the same effect is brought about by the fresh breezes from the cooler regions to the southward.  It is reasonable to suppose, that this fortunate complexion of the heavens is principally owing to the neighbourhood of those vast mountains called the Andes, which, running nearly parallel to the shore, and at a small distance from it, and extending immensely higher than any other mountains upon the globe, form upon their sides and declivities a prodigious tract of country, where, according to the different approaches to the summit, all kinds of climates may be found at all seasons of the year.

These mountains, by intercepting great part of the eastern winds, which generally blow over the continent of South America, and by cooling that part of the air which forces its way over their tops, and by keeping besides a large portion of the atmosphere perpetually cool, from its contiguity to the snows by which they are always covered, and thus spreading the influence of their frozen crests to the neighbouring coasts and seas of Peru, are doubtless the cause of the temperature and equability which constantly prevail there.  For, when we had advanced beyond the equinoctial to the north, where these mountains left us, and had nothing to screen us to the eastward but the high lands on the Isthmus of Darien, which are mere mole-hills compared to the Andes, we then found that we had totally changed our climate in a short run; passing, in two or three days, from the temperate air of Peru, to the sultry and burning atmosphere of the West Indies.