mules loaded with the snow of Orizaba arrive in full trot at Vera Cruz, more than the half of the snow is nevertheless melted during the road, the temperature of the atmosphere being constantly in summer, from 29° to 30° degrees of the centigrade thermometer *. Notwithstanding these obstacles, the inhabitants of the coast may daily procure sherbets of ice water. This advantage which is not possessed in the West India Islands, at Carthagena, and Panama, is of the greatest consequence to a town which is daily frequented by men born in Europe, and on the central table land of New Spain.

Although the yellow fever is not dangerous by immediate contact at Vera Cruz, and it is in no wise probable that it ever was introduced there from any other placet, it is not the less certain that it only appears at certain periods, without any discovery having yet been made of the modifications of atmosphere which under

*From 84° to 86° of Fahr. Trans.

+ "Vera Cruz neither received the germ of this cruel "disease from Siam nor from Africa, nor from the West “India Islands, nor from Carthagena, nor from the United "States; this germ was produced (engendrado) in its own "territory; and it always exists there though it only deve"lopes itself under the influence of certain climatical cir"cumstances." Comoto in his Informe al prior del consulado de la Vera Cruz, del mes de Junio, 1803. (MS.)

the torrid zone produce these periodical changes. It is to be regretted that the history of the epidemics does not go farther back than half a century. The great military hospital

of Vera Cruz was established in December 1764, but in no document preserved in the archives of that hospital is any mention made of the diseases which preceded the vomito of 1762. This epidemic which began under the viceroyship of the Marquis de Croix continued its ravages till 1775, when after paving the streets of Vera Cruz they made some feeble attempts to diminish the extreme dirtiness of the town. The inhabitants at first imagined that the pavement would increase the insalubrity of the air by augmenting, from the reverberation of the solar rays, the insupportable heat which prevails within the town; but when they saw that the vomito did not make its appearance from 1776 to 1794, they then believed that this pavement had secured them for ever from it, without reflecting that the marshes of stagnant water situated to the south and east of the town, continued to pour into the atmosphere the putrid emanations which in all times were regarded at Vera Cruz as the principal focus of the deleterious miasmata. It is a very remarkable fact, that during the eight years which preceded 1794, there was not a single example of vomito, although the concourse of

VOL. IV.

Europeans and Mexicans from the interior was extremely great, and the sailors not seasoned to the climate, gave themselves up to the same excesses which are now laid to their charge, and although the town was not so clean as it has been since the year 1800.

The cruel epidemic which appeared in 1794, began with the arrival of three vessels of war, the ship El Mino, the frigate Venus, and the howker Santa Vibiana, which had all touched at Porto Rico. As these vessels contained a great number of young sailors not seasoned to the climate, the vomito commenced then at Vera Cruz with extreme violence. Between 1794 and 1804, the disease re-appeared every year when the north winds ceased to blow. We see that between 1787 and 1794, the royal military hospital* only received 16,835 patients,

* This hospital receives all patients who come by sea. There were,

while between 1795 and 1802, their number had increased to 57,213. The mortality was very great, especially in 1799, when the Marquis de Branciforte the viceroy, dreading a disembarcation of the English on the eastern coast, ordered a number of troops to be cantoned in a very unhealthy place, at Aroyo Moreno, two leagues and a half from Vera Cruz.

We must observe that in the period which preceded the epidemic of 1794, the yellow fever never ceased to rage at the Havanah, and in the other West India Islands, with which the merchants of Vera Cruz constantly kept up commercial relations; and several hundreds of vessels annually came from these infected places without going quarantine, yet the vomito never appeared among the Europeans. I examined in the meteorological registers of M. Orta, month by month, the temperature of the year 1794; and far from being higher, it was ac

Before the commencement of the epidemic of 1794, the mortality was only 2 per cent. and now it is from six to seven per cent., and it would be still greater if this hospital did not receive, like every military hospital, many seamen whose diseases are not severe. In the civil hospitals of Paris, in a hundred patients, generally from fourteen to eighteen die; but we must not forget that these hospitals admit of a great number of patients on the point of death, or of a very advanced age. Travaux du bureau central d'admission, 1809. p. 5.

tuaally less than that of the preceding years, as is proved by the following table :

Mean temperature of Vera Cruz, (centigrade thermometer.)

The heat and humidity of the air may influence in two very different manners the developement of epidemics. They may favour the production of miasmata, or simply increase the irritability of the organs, and act as predisposing causes. From the facts which we have already related, it is impossible to deny