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vegetate abundantly under the latitude of Oaxaca and Mexico at a height of fifteen or sixteen hundred metres, are to be found in the provincias internas under the temperate zone in plains of inferior elevation. The height requisite for the different kinds of cultivation depends, in general, on the latitude of the places; but such is the flexibility of organization in cultivated plants, that with the assistance of the care of man they frequently break through the limits assigned to them by the naturalist.
Under the equator, the meteorological pheno, mena, such as those of the geography of plants
and animals, are subject to laws which are im. mutable and easily to be perceived. The climate there is only modified by the height of the place, and the temperature is nearly constant, notwithstanding the difference of seasons. As we leave the equator, especially between the 15th degree and the tropic, the climate depends on a great number of local circumstances, and varies at the same absolute height, and under the same geographical latitude. This influence of localities, of which the study is of such importance to the cultivator, is still much more manifest in the northern than in the southern hemisphere. The great breadth of the new continent, the proximity of Canada, the winds which blow from the north, and other causes already developed, give the equinoxial region of Mexico and the island of Cuba a particular character. One would say
that in these regions the temperate zone, the zone of variable climates, increases towards the south and passes the tropic of Cancer. It is sufficient here to state that in the environs of the Havanah (latitude 28° 8') the thermometer has been seen to descend to the freezing point at the small elevation of 80 metres * above the level of the oceant, and that snow has fallen near Valladolid (latitude 19° 42') at an absolute elevation of 1900 inetrest, while under the equator this last phe. nomenon is only observable at the double of the elevation.
These considerations prove to us that towards the tropic, where the torrid zone approaches the temperate zone (I use these improper names from their being consecrated by custom), the plants under cultivation are not subject to fixed and invariable heights. We might be led to distribute
* 262 feet. Trans.
+ M. Robredo has seen ice formed in a wooden trough in the month of January at the village of Ubajos, fifteen miles south-west from the Havanah, at an absolute elevation of 74 metres (242 feet). I myself saw, at Rio Blanco, the centigrade thermometer on the 4th January, 1801, at eight o'clock in the morning, at 7°, 5' above zero (45°, 5 of Fahrenheit). During the night an unfortunate negro perished of cold in a prison. However, the mean temperatures of the months of December and January in the plains of the island of Cuba are 17° and 18° (62o and 64° of Fahrenheit). All these determinations were made with excellent thermometers of Nairne.
6232 feet. Trans.
them according to the mean temperature of the places in which they vegetate, We observe, in fact, that in Europe the minimum of the mean temperature which a proper cultivation requires is for the sugar-cane, from 19° to 20°; for coffee 18°; for the orange 17°; for the olive 139,5' to 14°; and for the vine yielding wine fit to be drunk from 10° to 11° of the centigrade thermometer*, This thermometrical agricultural scale is accurate enough when we embrace the phenomena in their greatest generality. But numerous excep. tions occur when we consider countries of which the mean annual heat is the same, while the mean temperatures of the months differ very much from one another. It is the unequal division of the heat among the different seasons of the year which has the greatest influence on the kind of cultivation proper to such or such a latitude, as has been very well proved by M. Decandole f. Several annual plants, especially gramina with farinaceous seed, are very little affected by the rigour of winter, but, like fruit trees and the yine, require a considerable heat during summer. In part of Maryland, and es. pecially Virginia, the mean temperature of the year is equal and perhaps even superior to that of Lombardy; yet the severity of winter will not
allow the same vegetables to be there cultivated with which the plains of the Milanese are adorned. In the equinoxial region of Peru or Mexico, rye and especially wheat attain to no maturity in plains of 3500 or 4000 metres of elevation*, though the mean heat of these alpine regions exceeds that of the parts of Norway and Siberia, in which cerealia are successfully cultivated. But for about 30 days the obliquity of the sphere and the short duration of the nights render the summer heats very considerable in the countries in the vicinity of the polet, while under the tropics or the table-land of the Cordilleras the thermometer never remains a whole day above ten or twelve centigrade degrees. - To avoid mixing ideas of a theoretical nature and hardly susceptible of rigorous accuracy with faets, the certainty of which has been ascertained, we shall neither divide the cultivated plants in New Spain according to the height of the soil in which they vegetate most abundantly, nor according to the degrees of mean temperature which they appear to require for their develope. ment: but we shall arrange them in the order of their utility to society. We shall begin with the
* 11,482 and 13,123 feet. Trans.
† At Umea in Westro-Botnia (latitude 63° 49') the extremes of the centigrade thermometer were, in 1801, in summer + 35°, in winter — 45°,7. M. Acerbi complains much of the great summer heats in the most northern part of Lapland.
His state is even greatly preferable to that of the peasantry in a great part of the north of Europe. There are neither corvées nor villanage in New Spain ; and the number of slaves is next to nothing. Sugar is chiefly the produce of free hands. There the principal objects of agricul. ture are not the productions to which European luxury has assigned a variable and arbitrary value, but cereal gramina, nutritive roots, and the agave, the vine of the Indians. The appearance of the country proclaims to the traveller that the soil nourishes him who cultivates it, and that the true prosperity of the Mexican people neither depends on the accidents of foreign commerce, nor on the unruly politics of Europe.
Those who only know the interior of the Spanish colonies from the vague and uncertain notions hitherto published will have some difficulty in believing that the principal sources of the Mexican riches are by no means the mines, but an agriculture which has been gradually ameliorating since the end of the last century. Without reflecting on the immense extent of the country, and especially the great number of provinces which appear totally destitute of precious metals, we generally imagine that all the activity of the Mexican population is directed to the working of mines. Because agriculture has made a very considerable progress in the capitania general of Caraccas, in the kingdom of