high temperature of the atmosphere, and the resulting influence of both, and of the diet and regimen adopted, upon the constitution.

The diseases of warm climates are also those of temperate countries during very hot seasons, more particularly in situations the nature of which approaches to that generally observable within the tropics; they are, in short, the prevalent diseases of other climates rendered more intense by more powerful causes, and these more continued in their action, and much more prolonged, and hence their effects become more marked than elsewhere. From this it is apparent, that the practitioner in temperate regions, if he wish to extend his knowledge of disease generally, or if he even be desirous of becoming acquainted with the forms which disorders assume at particular seasons, should not overlook the study of those derangements because they are more frequently met with within the tropics, and because they have received the too limited appellation of intertropical diseases. That these derangements of the human frame are more frequently met with in warm climates, and less so in temperate countries, is merely the result of the general order of nature as regards the animal economy, and the human economy more particularly.

The finer shades of conformation and constitution, it should be farther remarked, are such as to adapt man to the circumstances and vicissitudes of the country in which Providence has ordained him to exist. This conformation is chiefly the result of the influences which have continued to operate on the parents; and the effect at last becomes conformable with the general character of the causes producing it. The European is constituted in a manner the best suited to the climate which he inhabits; and a similar conformation of the system of man to the circumstances of the country, may be traced in every part of the globe. When, however, man migrates from the climate which contributed to generate the peculiarities of his frame, to one which is remarkably different from that to which he is assimilated, then disorders of various kinds and grades may be expected. Those organs which changes and peculiarities of climate chiefly affect, soon become deranged in their functions; and when they continue disordered for any time, additional disease is generated in many of the other organs of the frame, especially in those which are more intimately allied in function to them. What is here inferred à priori is evident in practice, particularly upon an intimate view of the succession of the phenomena of disease. But the climate, and the circumstances more intimately connected with the climate and the soil, or vicissitudes of tempera

ture and of season, are not to be considered as the sole causes of disorder, for diseased actions proceed not always from these; and when they do apparently derive their origin from thence, other causes frequently co-operate with them in producing the effect. The modes of living, the diet and regimen of the individual, whose frame and constitution are unassimilated to the country, are generally as fertile causes of diseases as those which relate to the climate, inasmuch as they are but ill-adapted to the nature of the change which he has experienced, and to the peculiarities of his system, under the circumstances in which he has been recently placed; and these latter combine with the former class of causes in producing diseases which, but for this combination, might never have been occasioned. The individual who is, as it were, transplanted from the air and soil from which he has been, in a measure, formed, and in which he has longer vegetated, into those with respect to which he is quite an exotic,-instead of adopting the diet and regimen suited to the new circumstances into which he is placed, more generally pursues both the one and the other, according as the custom of those around him, or his own morbid appetites, seduce him. Although continually operated upon by causes, of whose influence his system is the more susceptible, the more recently he has undergone the change; although even the air which he breathes tends, at the same time that it animates, to modify his constitution to the new circumstances in which it is placed, and to generate disease in the process of transformation which is being effected; yet he more generally lives on as if he were entirely independent both of it and of the substances which he receives into his stomach; and, instead of adapting, in some degree, his diet and regimen to the climate in which he is placed, he is seduced by the sensations of his palate and his pleasures, which, when indulged in, occasion that condition of the system which, if not amounting to actual disease, is generally productive of it, under the most favourable circumstances of climate; and more especially during warm states of the atmosphere, and when it is loaded by moisture, terrestrial effluvia, and other causes of disorder.

CHAPTER I.

GENERAL VIEW OF THE CAUSES CHIEFLY PRODUCTIVE OF DISEASE IN WARM CLIMATES, PARTICULARLY IN INDIA.

PRIOR to entering upon a consideration of the particular diseases with which various organs of the human body are found to be most commonly affected in warm climates, it will be advantageous to take a view of those causes, to which the prevalence of disease, especially amongst the European and unseasoned inhabitants, are to be imputed. These cau es being ascertained, their effects may be more readily inferred, and the means of removing them, or of counteracting them, may be pointed out with stronger hopes of receiving due attention from those for whose benefit the remarks respecting them have been made.

In this Chapter, then, will be considered,

1st, The most productive sources of disease in warm countries, and in hot seasons in temperate climates, namely, exhalations proceeding from the soil and decayed vegetation under the various circumstances favouring their extrication.

2d, Those causes of disease which operate by disposing the system to become affected by the former more efficient class of causes, and which belong chiefly to the important topics of diet and regimen.

SECTION I.-On those Causes of Disease in Warm Climates which proceed from the Situation, Soil, and Vegetation of a Country.

When the obvious and intimate relations subsisting between the earth's surface and the human species-between man and the soil on which he moves, the productions of the earth which surround and feed him, and the air which he is constantly inhaling into his body are considered-the conditions of these agents, as far as they can be recognised by sensible properties, or inferred from their manifest effects, become matters of great interest in medical

science, and of surpassing importance, in philosophical, civil, and political points of view. The conditions of the atmosphere resulting from the states of, and the changes taking place within and upon, the soil covering the torrid and temperate zones of the globe, are not only the chief and immediate sources, on the one hand, of the strength and perfection of the mental and corporeal constitution of man; and, on the other, of the diseases which harass him, stunting his physical and moral growth, or sweeping him from amongst living animals, of which he is the head and master; but are also the most productive, although the more remote causes of national character-of advancement in all the arts, sciences, and refinements of life in some countries, and of moral and physical debasement in others. In one, their beneficent operation may be traced in the freedom, prosperity, and greatness of its inhabitants; in another, their noxious influences are manifest in the degenerate and debased condition of the species, whose wants, habits, enjoyments, and desires, seldom surpass those of the higher animals. In short, the constitutions of the atmosphere derived from soil and situation, according to their nature, are not only the productive sources of disease, but also the chief spring of the perfection of the human frame, and of its degeneracy -the influential causes of the various degrees of human science presented to us in the different kingdoms of the world-of the freedom and greatness of nations, and of their enslaved and degraded conditions-of the rise and downfall of empires. They should equally interest the scientific physician, the philosopher, the enlightened legislator, and the arbiters of the fates of nations.

From a consideration of the extensive influence exerted by the states of the atmosphere on the physical and moral constitution of man, let us proceed to inquire into the soils, situations, and circumstances, producing terrestrial effluvia, which, mixing with the lower strata of the atmosphere, diminish its purity, and injuriously affect the human frame.

Of the various soils and situations productive of miasmata, the most deserving of notice, are low and marshy places. All situations within the tropics, or the temperate zones, which are low and subject to inundations, and places which are saturated with moisture, and abounding with the exuviæ of organic substances, are productive of unwholesome effluvia. Argillaceous soils, and the deep and rich alluvial earth which is found in the bottoms of valleys or ravines, and on the banks, or at the mouths of rivers, are also productive of miasmata whenever they are exposed to the action of a

powerful sun, particularly after they have been inundated, and when they abound with the remains of a luxuriant vegetation.

We have accounts, in the writings of the ancients, of the insalubrity of situations in temperate climates, such as have been now instanced; and daily observations in the south and middle of Europe, even, furnish us with numerous proofs of the same fact, and of various others closely allied to it. Several instances of the unhealthiness of marshy districts are to be met with in the works of Hippocrates. In his "Epidemics" we are told that the city of Abydos had been several times depopulated by fever, but the marshes being drained by his advice, it became healthy. The majority of the ancient writers present us with facts evidently pointing to the pernicious effects of low and marshy situations. The plague at Athens, which is almost medically described by Thucydides, may be rationally imputed to this source; and the pestilences, mentioned in the Roman writers as having visited Rome, can best be explained by assigning the exhalations proceeding from the surrounding marshes and low grounds, and from the occasional inundations of the Tiber, as their cause. The accounts given by Dionysius of Halycarnassus, by Plutarch, and by Livy, evidently show that the causes of disease, now to be considered, were known both to the historians and physicians of antiquity; and numerous instances may be adduced to show, that the means of removing and counteracting them were as well understood as at the present day. The lake Averna, mentioned by Virgil, is probably a poetical exaggeration of the effects arising from marshes; and the deeds of Hercules, the metaphorical record of his success in removing these most productive sources of disease. Strabo speaks very confidently of the good effects of the embankments of rivers, of drainage, and roads, in removing the causes of pestilence: and the groves, which were held sacred by the ancients, had obviously, in the majority of cases, the effect of confining the range of the miasmata generated by the adjoining marshes, and of protecting the inhabitants of the towns and villas in their vicinity.

The insalubrity of those situations of which we read in the works of the ancients, is still more fully shown in the writings of modern observers. And it is probable that those places have actually become more unhealthy than they were in former times, owing to the accession of alluvial soil which they may have received from the higher grounds in their vicinity, and from the depositions of soil at the mouths of rivers and in the bottom of lakes, thus converting a healthy lake to a marsh; to the removal of those screens or cur