But The Difference Of Climate Observable Between Places So Near Each Other Is Perhaps Less Owing To Comparative Height Than To Local Circumstances.

Among these causes we may cite the proximity of the forests; the frequency of descending currents, so common in these valleys, closed on every side; the abundance of rain; and those thick fogs which diminish during a great part of the year the direct action of the solar rays.

The decrement of the heat being nearly the same within the tropics, and during the summer under the temperate zone, the small difference of level of one hundred toises should produce only a change in the mean temperature of 1 or 1.5 degrees. But we shall soon find that at Cumanacoa the difference rises to more than four degrees. This coolness of the climate is sometimes the more surprising, as very great heat is felt at Carthago (in the province of Popayan); at Tomependa, on the bank of the river Amazon, and in the valleys of Aragua, to the west of Caracas; though the absolute height of these different places is between 200 and 480 toises. In plains as well as on mountains the isothermal lines (lines of similar heat) are not constantly parallel to the equator, or the surface of the globe. It is the grand problem of meteorology to determine the inflections of these lines, and to discover, amid modifications produced by local causes, the constant laws of the distribution of heat.

The port of Cumana is only seven nautical leagues from Cumanacoa. It scarcely ever rains in the first-mentioned place, while in the latter there are seven months of wintry weather. At Cumanacoa, the dry season begins at the winter solstice, and lasts till the vernal equinox. Light showers are frequent in the months of April, May, and June. The dry weather then returns again, and lasts from the summer solstice to the end of August. Then come the real winter rains, which cease only in the month of November, and during which torrents of water pour down from the skies.

It was during the winter season that we took up our first abode in the Missions. Every night a thick fog covered the sky, and it was only at intervals that I succeeded in taking some observations of the stars. The thermometer kept from 18.5 to 20 degrees, which under this zone, and to the sensations of a traveller coming from the coasts, appears a great degree of coolness. I never perceived the temperature in the night at Cumana below 21 degrees. The greatest heat is felt from noon to 3 o'clock, the thermometer keeping between 26 and 27 degrees. The maximum of the heat, about two hours after the passage of the sun over the meridian, was very regularly marked by a storm which murmured near. Large black and low clouds dissolved in rain, which came down in torrents: these rains lasted two or three hours, and lowered the thermometer five or six degrees. About five o'clock the rain entirely ceased, the sun reappeared a little before it set, and the hygrometer moved towards the point of dryness; but at eight or nine we were again enveloped in a thick stratum of vapour. These different changes follow successively, we were assured, during whole months, and yet not a breath of wind is felt. Comparative experiments led us to believe that in general the nights at Cumanacoa are from two to three, and the days from four to five centesimal degrees cooler than at the port of Cumana. These differences are great; and if, instead of meteorological instruments, we consulted only our own feelings, we should suppose they were still more considerable.

The vegetation of the plain which surrounds the town is monotonous, but, owing to the extreme humidity of the air, remarkable for its freshness. It is chiefly characterized by an arborescent solanum, forty feet in height, the Urtica baccifera, and a new species of the genus Guettarda.* (* These trees are surrounded by Galega pilosa, Stellaria rotundifolia, Aegiphila elata of Swartz, Sauvagesia erecta, Martinia perennis, and a great number of Rivinas. We find among the gramineous plants, in the savannah of Cumanacoa, the Paspalus lenticularis, Panicum ascendens, Pennisetum uniflorum, Gynerium saccharoides, Eleusine indica, etc.) The ground is very fertile, and might be easily watered if trenches were cut from a great number of rivulets, the springs of which never dry up during the whole year. The most valuable production of the district is tobacco. Since the introduction of the farm* (* Estanco real de tabaco, royal monopoly of tobacco.) in 1779, the cultivation of tobacco in the province of Cumana is nearly confined to the valley of Cumanacoa; as in Mexico it is permitted only in the two districts of Orizaba and Cordova. The farm system is a monopoly odious to the people. All the tobacco that is gathered must be sold to government; and to prevent, or rather to diminish fraud, it has been found most easy to concentrate the cultivation in one point. Guards scour the country, to destroy any plantations without the boundaries of the privileged districts; and to inform against those inhabitants who smoke cigars prepared by their own hands.

Next to the tobacco of the island of Cuba and of the Rio Negro, that of Cumana is the most aromatic. It excels all the tobacco of New Spain and of the province of Varinas. We shall give some particulars of its culture, which essentially differs from the method practised in Virginia. The prodigious expansion which is remarked in the solaneous plants of the valley of Cumanacoa, especially in the abundant species of the Solanum arborescens, of aquartia, and of cestrum, seems to indicate the favourable nature of this spot for plantations of tobacco. The seed is sown in the open ground, at the beginning of September; though sometimes not till the month of December, which period is however less favourable for the harvest. The cotyledons appear on the eighth day, and the young plants are covered with large leaves of heliconia and plantain, and shelter them from the direct action of the sun.

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