CHAPTER VI. CLIMATE OF BUENOS AYRES, AND ITS EFFECTS. Climate of Buenos Ayres, liable to sudden changes. Influence of the North Wind. Case of Garcia. Effects of a Pampero. Dust-Storms and Showers of Mud. The Natives free from Epidemics, but liable to peculiar affections from the state of the atmosphere. Lockjaw of very common occurrence. The Smallpox stopped by Vaccination. Introduced in 1805, and preserved by an individual. Its first introduction amongst the Native Indians by General Rosas. Cases of Longevity, of frequent occurrence. Azara, the best of all writers upon the country, has with much truth observed that the climate of Buenos Ayres is governed not so much by its latitude as by the wind, a change of which will continually produce an alteration of from 20 to 30 degrees in the thermometer[16]? I have been often asked whether the heats in summer are not almost intolerable. On some days they are so; the glass perhaps above 90° in the shade, and all nature gasping for air; but on those very days the most experienced of the natives will be clothed in warm woollens instead of linen jackets and trousers, for fear of catching cold. During the greater part of the year the prevailing winds are northerly, which, passing over the marshy lands of Entre Rios, and then over the wide expanse of the Plata, imbibe their exhalations, and, by the time they reach the southern shores of the river, have a great influence upon the climate. Everything is damp: the mould stands upon the boots cleaned but yesterday; books become mildewed, and the keys rust in one's pocket. Good fires are the best preservatives, and I found them, if not absolutely necessary, at least very comfortable, during quite as many months as I should have had them in England; and yet I never, during nine years, saw snow, or ice thicker than a dollar, and the latter only once. Upon the bodily system the effect produced by this prevailing humidity is a general lassitude and relaxation; opening the pores of the skin, and inducing great liability to colds, sore throats, rheumatic affections, and all the consequences of checked perspiration; one of the best safeguards against which is doubtless the woollen clothing of the natives, of which I have already spoken; though they require it, perhaps, the more especially, because they seldom stir out of their houses in the extreme heat of the day; and it is at the time they do go out, when the sun has lost its power and the damps of evening are setting in, that such precautions are doubly necessary. Europeans, at first, are loth to take the same care of themselves, but sooner or later they discover that the natives are right, and insensibly fall into their ways.