neighbouring mountains wherever the rock is covered with earth. Farms are established in the neighbourhood of the mine. The high price of provision, from the competition of the purchasers, indemnifies the cultivator for the priva tions to which he is exposed from the hard life of the mountains. Thus from the hope of gain alone, and the motives of mutual interest, which are the most powerful bonds of society, and without any interference on the part of the government in colonization, a mine which at first appeared insulated in the midst of wild and desert mountains, becomes in a short time connected with the lands which have long been under cultivation.

Moreover, this influence of the mines on the progressive cultivation of the country is more du rable than they are themselves. When the seams are exhausted, and the subterraneous operations are abandoned, the population of the canton undoubtedly diminishes, because the miners emigrate elsewhere; but the colonist is retained by his attachment for the spot where he received his birth, and which his fathers cultivated with their hands. The more lonely the cottage is, the more it has charms for the inhabitant of the mountains. It is with the beginning of civilization as with its decline: man appears to repent of the constraint which he has imposed on himself by entering into society; and he loves solitude because it restoreș to him his former freedom. This moral tendency,

this desire for solitude, is particularly manifested by the copper-coloured indigenous, whom a long and sad experience has disgusted with social life, and more especially with the neighbourhood of the whites. Like the Arcadians, the Aztec people love to inhabit the summits and brows of the steepest mountains. This peculiar trait in their disposition contributes very much to extend population in the mountainous regions of Mexico. What a pleasure it is for the traveller to follow these peaceful conquests of agriculture, and to contemplate the numerous Indian cottages dispersed in the wildest ravins, and necks of cultivated ground advancing into a desert country between naked and arid rocks!

The plants cultivated in these elevated and solitary regions differ essentially from those cultivated on the plains below, on the declivity and at the foot of the Cordilleras. I could treat of the agriculture of New Spain, following the great divisions which I have already laid down in sketching the physical view of the Mexican territory; and I could follow the lines of cultivation traced on my geological sections, of which the elevations have partly been indicated in the third chapter*; but it is to be observed that these lines of cultivation, like that of the perpetual snows to which they are parallel, sink towards the north, and that the same cerealia, which only

* See vol. I. p. 68.

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 immutable 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 23° 8') the thermometer has been seen to descend to the freezing point at the small elevation of 80 metres above the level of the ocean †, and that snow has fallen near Valladolid (latitude 19° 42′) at an absolute elevation of 1900 metres, while under the equator this last phenomenon 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

+ 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 7o, 5′ above zero (45o, 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° (62° and 64° of Fahrenheit). All these determinations were made with excellent thermometers of Nairne.

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 13°,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 exceptions 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. Decandolet. Several annual plants, especially gramina with farinaceous seed, are very little affected by the rigour of winter, but, like fruit trees and the vine, require a considerable heat during summer. In part of Maryland, and especially Virginia, the mean temperature of the year is equal and perhaps even superior to that of Lombardy; yet the severity of winter will not

* From 66° to 68°; 64°; 62°; from 56°.3 to 57°; and from 50° to 51°.8 of Fahrenheit. Trans.

+ Flore françoise, troisieme edition, t. II. p. x.