It is useful, not only to study different countries with respect to their salubrity, but also to observe the different situations in the same locality, and the different quarters of the same city. M. Junod presented to the Academy of Sciences, some years since, an essay on this subject, which is full of interest. In considering the distribution of the population in large cities, we are struck by the tendency of the wealthy class to move toward the western portions, abandoning the opposite side to the industrial pursuits, It seems to have divined, by a kind of intuition, the locality which would have the greatest immunity in the time of sore public calamities. For example, let us speak first of Paris. From the foundation of the city, the opulent class has constantly directed its course toward the west. It is the same in London, and generally, in all the cities of England. At Vienna, Berlin, St. Petersburg, and, indeed, in all the capitals of Europe, this same fact is repeated; there is the same movement of the rich toward the west, where are assembled the palaces of the kings, and the dwellings for which only pleasant and healthy sites are desired.
In visiting the ruins of Pompeii and other ancient cities, I have observed, as well as M. Junod, that this custom dates from the highest antiquity. In those cities, as is seen at Paris in our day, the largest cemeteries are found in the eastern parts, and generally none in the western. M. Junod, examining the reason of so general a fact, thinks it is connected with atmospheric pressure. When the mercury in the barometer rises, the smoke and injurious emanations are quickly dispelled in the air. When the mercury lowers, we see the smoke and noxious vapors remain in the apartments and near the surface of the earth. Now every one knows that, of all winds, that from the east causes the mercury in the barometer to rise the highest, and that which lowers it most is from the west. When the latter blows, it carries with it all the deleterious gases it meets in its course from the west. The result is, that the inhabitants of the eastern parts of a city not only have their own smoke and miasmas, but also those of the western parts, brought by the west wind. When, on the contrary, the east wind blows, it purifies the air by causing the injurious emanations to rise, so that they cannot be thrown back upon the west. It is evident, then, that the inhabitants of the western parts receive pure air from whatever quarter of the horizon it comes. We will add, that the west wind is most prevalent, and the west end receives it all fresh from the country.
From the foregoing facts, M. Junod lays down the following directions: First, persons who are free to choose, especially those of delicate health, should reside in the western part of a city. Secondly, for the same reason, all the establishments that send forth vapors or injurious gases should be in the eastern part. Thirdly and finally, in erecting a house in the city, and even in the country, the kitchen should be on the eastern side, as well as all the out-houses from which unhealthy emanations might spread into the apartments.
M. Elie de Beaumont has since mentioned some facts which tend to prove the constancy and generality of the rule laid down by M. Junod. He noticed in most of the large cities this tendency of the wealthy class to move to the same side—generally, the western—unless hindered by certain local obstacles. Turin, Liége, and Caen are examples of this. M. Moquin-Tandon has observed the same thing at Montpellier and at Toulouse. Paris and London also present analogous facts, although the rivers which traverse those two great centres flow in a diametrically different direction. Paris increased in a north-easterly direction at the time when the Bastille, the Palais des Tournelles, the Hotel St. Paul, etc., were built; but the inhabitants were then influenced by fear of the aggressive Normans, whose fleets ascended the Seine as far as Paris, and were only arrested by the Pont-au-Change. At that time, and as long as this fear lasted, they must have felt unwilling to live in Auteuil or Grenelle, But since the foundation of the Louvre, and especially since the reign of Henri Quatre, the current has resumed its normal direction. M. Elie de Beaumont is inclined to believe that, among the causes of this phenomenon, we should reckon the temperature and the hygrometrical state of the air, which is generally warmer and more moist during the winds from the west and south-west than during the east and north-east winds.
What most contributes to prolong existence is a certain uniformity in heat and cold, and in the density and rarity of the atmosphere. This is why the countries in which the barometer and thermometer are subject to sudden and considerable changes are never favorable to the duration of life. They may be healthy, and man may live a long time there; but he will never attain a very advanced age, because the variations of the atmosphere produce many interior changes which consume, to a surprising degree, both the strength and the organs of life.
Too much dryness or too much humidity are equally injurious to the duration of life; yet the air most favorable to longevity is that which contains a certain quantity of water in dissolution. Moist air being already partly saturated, absorbs less from the body, and does not consume it as soon as a dry atmosphere; it keeps the organs a longer time in a state of suppleness and vigor; while a dry atmosphere dries up the fibres and hastens the approach of old age. It is for this reason, doubtless, that islands and peninsulas have always been favorable to old age. Man lives longer there than in the same latitude upon continents. Islands and peninsulas, especially in warm climates, generally offer everything that contributes to a long life: purity of air, a moist atmosphere, a temperature often at one's choice, wholesome fruit, clear water, and a climate almost unvariable. I had an opportunity, long desired, of traversing the ocean as far the Tristan Islands, and of returning to the Indian Ocean by doubling the Cape of Good Hope with a captain who wished to observe the different islands on the way. I was thus able, in going as well as returning, to visit these numerous islands, and I can speak of them from reasonable observation. But it is sufficient to mention, from a hygienic point of view, the Isle of Bourbon, (where I lived for many years,) to give an idea of the sanitary condition of islands in general. Like most isles, the Isle of Bourbon has a form more or less pyramidal. The shore, almost on a level with the sea, is the part principally inhabited. There are few villages in the interior of the island, but many private residences. The temperature on the shore, though very high, is less intense than is supposed: the medium temperature being between 40° and 50°. The sea and land breezes, which succeed each other morning and evening, refresh the atmosphere and maintain a healthy moisture. It hardly ever rains except during the winter, Besides, it is very easy to choose the temperature one prefers. As the mountains are very lofty, they afford every season at once. On the summit are seen snow and ice, while at the foot the heat is tropical; so that it is sufficient to ascend for ten or fifteen minutes to find a marked change of temperature, And the colonists of but little wealth are careful to profit by this precious favor of nature. They select two or three habitations at different heights, in order to enjoy a continual spring, During the cool season, they reside on the sea-shore. Then they go to their dwelling a little above, where the temperature is mild. And in the hot season, they ascend to still higher regions.
It is impossible to express the pleasure of thus having several dwellings at one's choice, in some one of which desirable temperature can be enjoyed in any season. I had three: one at St. Denis, capital of the colony, one at La Rivière-des-Pluies, and another at La Ressource. La Rivière-des-Pluies, belonging to M. Desbassayns, a venerable old man and president of the general council, is the finest situation on the island. It was formerly called the Versailles of Bourbon. I inhabited a summer-house above which the surrounding trees crossed their tufted branches, forming a dome of verdure in which the birds came to warble. Regular alleys, extending as far as the eye could reach, formed by superb mango-trees, were enclosed by parterres, groves, gardens, woods, and all the surroundings of a small village. Each large habitation in the colony had every resource within itself, and was the faithful copy of the old feudal castles.
La Ressource, a dwelling for the hottest season, belonging also to M. Desbassayns, presented another kind of beauty. There was less artistic luxury about it, but nature had lavished on it all her splendor. After dinner, admiring the panorama which was spread out as far as the horizon, I remarked to M. Desbassayns that I did not believe it possible for the entire world of nature to furnish a more beautiful perspective. "I have travelled a great deal," said he, "and in truth I have never seen anything like it, not even from the most magnificent points of view in America." The venerable old man then took me by the arm and invited me to visit his estate. He made me first look at his woods, with their tufted foliage; the cane-fields; the deep ravines; the streams, with their windings rising one above the other in such a manner that the lower ones were perfectly visible, and extending in successive circuits more or less varied to the shore of the sea, which gleamed like a mirror as far as the eye could reach, and upon the azure surface of which stood clearly out, like silver clouds, the white sails from all parts of the world which had given each other rendezvous here, and were constantly approaching this isle of lava, flowers, shadows, and light, which they had taken as the centre of réunion.
He made me afterward notice the verdant fields which had formerly belonged to the parents of Virginia, the heroine of the romance of Bernardin de St. Pierre. He related to me the true history of Virginia, who was his cousin. Her death happened nearly as described by the celebrated romancer. He made me notice, upon his genealogical tree, the branch that bore upon one of its leaves the name of Virginia!
M. Desbassayns had promised me some reliable notes respecting her, and I was glad to offer them to my illustrious friend, Count Alfred de Vigny, who, in giving me a farewell embrace, had commissioned me to bear his most tender expressions of love to the region which had inspired the touching narrative of St. Pierre. But alas! remorseless death warns us to remember the uncertainty of life, even when everything disposes us to forget it.