ture. It is in vain in the present imperfect state of meteorology Temperato attempt an explanation of the atmospheric phenomena, connected with climate; it may be sufficient to quote the results of observations concerning the mean temperature of different places in France. different plants. These different results prove that several local causes, Regions of such as the elevation of the soil, its exposure, the vicinity of seas and mountainous chains, have a considerable influence on the temperature and humidity of the atmosphere. The indications offered by different plants are less liable to error, and the climate of France may thus be better determined. The olive, maize and the vine form the limits of four natural regions into which the country is divided; these limits have been marked on different maps by straight and parallel lines, but in reality they are always curved or sin The above results are still considered doubtful. The degrees are those of the centigrade thermometer; to convert them into degrees of Fahrenheit, it is necessary to multiply them by 9-5ths, and then to add the number 32. BOOK Winds. Rain. in the temperate zone, not so much from the latitude, as from the moderate elevation of the soil; still, however, different parts of it are exposed to changes of temperature, that exhibit their influence on vegetation. The humid vapours that rise from the seas, which bound France on the west, and the mountainous chains that limit on the east and the south, often occasion sudden modifications in the atmosphere. The winds, according to the different directions from which they proceed, are accompanied with hail, rain and drought in the different basins. As the north wind in the valley of Durance, does not pass over any great heights, it tempers the heat of the climate, and is favourable to the growth of plants; but the same wind is often attended with destructive effects on the basins of the Seine and the Loire. While the valley of the Durance is desolated by the east wind, that traverses the frozen summits of the Alps, it is the sign and harbinger of fair weather in the country watered by the Seine. The south winds that issue from the burning deserts of Africa spread desolation on the coasts of the Mediterranean; cooled in their passage over the snowy summits of the Pyrenees, they are frequently accompanied with hail in the basin of the Garonne. The crops in the departments of Var and Bouches du Rhone are often laid waste by the mistral, a south-east wind known by the name of galerne near the mouth of the Loire; in Brittany, on the contrary, it as well as the south-west wind are often forerunners of rain. Lastly, the north-east wind is accompanied with cold and humid weather in the departments of Vosges and Ardennes. France is divided into two great regions by the forty-sixth parallel, and there is a sensible difference in the mean number of rainy days on the north and south of the same line, which passes along the northern declivities in the group of Mont Dor. On the south the mean number is equal to 134 rainy days, and at the latitude of Paris, to 105. From the observations made in order to ascertain the mean quantity of rain that falls in different parts of France, the following esults have been derived. ture. It is in vain in the present imperfect state of meteorology Temperato attempt an explanation of the atmospheric phenomena, connected with climate; it may be sufficient to quote the results of observations concerning the mean temperature of different places in France. different plants. These different results prove that several local causes, Regions of such as the elevation of the soil, its exposure, the vicinity of seas and mountainous chains, have a considerable influence on the temperature and humidity of the atmosphere. The indications offered by different plants are less liable to error, and the climate of France may thus be better determined. The olive, maize and the vine form the limits of four natural regions into which the country is divided; these limits have been marked on different maps by straight and parallel lines, but in reality they are always curved or sin The above results are still considered doubtful. The degrees are those of the centigrade thermometer; to convert them into degrees of Fahrenheit, it is necessary to multiply them by 9-5ths, and then to add the number 32. CXLI. BOOK - uous; they follow the declivities and windings occasioned by the inequalities in the soil, and cut obliquely the degrees of latitude. The region of olives extends from the shores of the Mediterranean, from the eastern declivities of the Pyrenees, the southern of the Cevennes, and the western of the Lower Alps. It is bounded on the north by a line which, commencing at Bagneres-de-Luchon, extends in a straight direction to Dié in the department of Drome, and winds to Embrum in the department of the High Alps. The region of maize does not extend beyond a second line, which begins at the mouth of the Gironde, and, passing to the north of Nevers, stretches to the northern extremity of Alsace. The vine occupies both these regions, but does not succeed beyond a line at some leagues northwards from the mouth of the Loire; the same line produced towards the north-cast, passes to the south of the sources of the Eure, follows the contours of the heights which bound the right bank of the Oise, stretches on the north of the Aisne and Verdun, and terminates on the north-east at the Rhine. Beyond this boundary the vine gives place to the apple, but the limits must not be considered rigorously exact. Thus, maize might be cultivated in the country round Metz, for it thrives in the gardens; a considerable quantity is indeed cultivated in Brittany on the southern declivities of the Arce heights. Influence of the sea. The neighbourhood of the sea, by rendering the climate milder, extends its influence to vegetation; the fig and the myrtle, which seem to require a warm climate, flourish in very different latitudes. The first needs no shelter, and yields excellent fruit in the neighbourhood of Havre and Cherburg, while the same plant not only requires a favourable exposure in the vicinity of Paris, but the fruits are later and never so good. The myrtle grows in the open air in Cotentin, at Brest, and Belle-Ile-en-Mer. At a hundred leagues farther south, but at a greater distance from the sea, it does not resist the severity of the climate without much care. The melon grows almost without culture on the coasts of Lower Normandy, and it is well known how much labour is bestowed on it in the neighbourhood of Paris, where, however, some sorts are produced, that surpass the best in Italy. BOOK CXLI. Lastly, the height of the soil has a great influence on difHeight of ferent plants; thus the chestnut tree flourishes from the the soil. mountains of Forez and Auvergne to the southern extremi ties of France, and grows naturally in several woods round Paris.* The only useful plants really natural to France, are the Plants infig, the apple, the pear and the plum; it ought not perhaps France. to be forgotten that among the acotyledones, the truffles in the neighbourhood of Angouleme and Perigueux, so much prized by gourmands, are indigenous to the country. Many useful plants have been naturalized by culture; the cherry tree brought from Asia by Lucullus, was as well as the vine, first planted in France by the Romans. The Greek colonists on the coasts of the Mediterranean transported the olive, a plant indigenous to Mount Taurus, and the raspberry-bush from Mount Ida. Since the discovery of the New World, France has obtained the acriviola of Peru, the lycopersicon of Mexico, the potato of Virginia, and the maize which has been incorrectly called Turkey corn. The humble parsley has been brought from Sardinia, and the cardoon from Barbary. The pomegranate was conveyed from Africa, and planted in the southern regions of France. The gardens, the orchards and fields in the same country, are now adorned with the productions of Asia; the orange, the lemon and the white mulberry are indigenous to China; the black mulberry to Asia Minor, the apricot to Armenia, and the peach to Persia. Other plants first imported from Asia are now common, such as the almond, the walnut and the finest kind of melons. Lastly, the kidney bean, white endive and lettuce have passed from the burning climate of India to the temperate, countries of western Europe. The gardener has been enabled See the Flore Francaise by M. de Candole, tom. ii. + M. Moreau de Jones, corresponding member of the Academie des Sciences, read a paper in 1828 to the Academy, in which he proved the American origin maize. |