falls between the tropics has often been considered a fruitful cause of disease. During the hours of from seven to eleven o'clock on a clear calm night, I have know the dew to fall so heavily as to have been sensible to the feeling, to have given to the pavement the appearance of a slight shower having fallen, and to have drenched the brushwood with moisture. It has been described as offensive to the smell: this is not the case the unpleasant odour occasionally perceived during a heavy fall of dew in certain places arises from other causes, which I shall attempt to explain in another part. Except immediately preceding one of those dreadful scourges of the West Indies, a hurricane, the barometrical changes are imperceptible, the mercury always remaining opposite 29.50 on the scale of the instrument.

Towards the centre of the island, on the leeward side, is found what in the language of the country is called the souffre; it is the crater of a former volcano, and consists of a valley filled with aluminous earth, combined with sulphurous acid, and native sulphur. In the centre are several cauldrons of water in a state of constant ebullition, and evolving at the same time quantities of sulphuretted hydrogen and sulphurous acid gases. The little town of Soufriere in the neighbourhood is so impregnated with the former of these gases, that the silver plate in the houses cannot be preserved bright for half an hour, and paint which contains the carbonate of lead, is decomposed and changes its colour in a single night, from exposure to the atmosphere.

Castries, the principal town of the island, is situated on its leeward side, at the bottom of a deep and narrow bay, on a plain scarcely elevated above the level of the sea, and in many places even lower. It is surrounded by hills of considerable elevation, which are intersected here and there by ravines. Those parts of the town in the immediate vicinity of the sea have been formed artificially by filling up the shallow water of what was formerly a lagoon. The plain immediately to windward serves during the dry season as a parade-ground for the militia; it is entirely uncultivated and swampy. From the north to the east the town is bounded by extensive fens filled

with mangrove trees, and covered partially at high tide by the sea. To the southward it is bounded by the river, the lagoon, and the burying-ground, the lower parts of which are often inundated, always humid, and covered by a luxuriant but rank vegetation. It is well paved for the most part, with a kennel running through the centre of each street; these, partly from the low situation of many parts of the town, and partly also for want of proper police regulations, are often exceedingly filthy.

Viewed from any part of the surrounding heights, about sunrise Castries appears to be buried in a thick canopy of dense vapour, arising from the swamps and marshy grounds which surround it. This accounts for the sensation of a damp, unhealthy coldness often felt at or before sunrise-a coldness, however, which is not indicated by the thermometer. As the sun rises, this mist or fog is either dissipated by his rays, or is blown to leeward by the wind.

The garrison of Morne Fortuné is situated upon a high hill to the southward of the town, rising abruptly above it to the height of 800 feet; the difference of temperature averages about 4. St. Lucia is considered one of the most unhealthy of the West India islands, and there are certain parts of it which most assuredly merit this unenviable celebrity, amongst which the town of Castries is one. To account for this, I have given this short sketch of its topography and climate; and we see that it abounds in all the generally acknowledged sources of the tropical fevers. We have an elevated temperature, imperfect ventilation, humidity, and malaria from every attributable origin. We will now examine all these causes in succession, and ascertain, as far as we are able, their effects upon the human body.

CHAPTER III.

MALARIA.

THIS name is given at the present day to a peculiar principle, with the nature of which we are as yet unacquainted, but to the effects of which the febrile endemics, particularly those of an intermittent or remittent type, that at different periods have been seen to obtain in certain parts of the world, have been and still are almost universally attributed. By the bulk of physicians it is supposed to arise from animal or vegetable matters, or both united, in certain states and stages of decomposition. It is true that this opinion is not universal. Dr. Fergusson attributes the origin of this poison to water during the process of drying. This gentleman says that "one only condition is indispensable to its production, and that is the paucity of water, where it has recently abounded. It is the drying margins of the lake or pool from which this poison uniformly emanates, and never from the body; and he thinks that it may be fairly presumed that water, for as long as it can preserve the figure of its particles above the surface, is innoxious, and that it must first be absorbed into the soil and disappear to the eye, before it can produce any mischievous effects."

Others have supposed that the causes which give rise to this poison exist in the emanations from ground of a volcanic formation, produced by the action of the sun's rays. These emanations, they state, contain quantities of deleterious gases, as sulphuretted hydrogen, carbonic acid, and azote, which affect the vital principles of the human frame. We will presently investigate the truth of these opinions. We must now examine the properties of malaria when arising from swamp, or from the decomposition of animal and vegetable matter.

Marsh or Swamp.

Both these terms are used to signify a tract of country of greater or less extent, the surface of which is habitually covered

with stagnant water, and the soil underneath is formed of a clay mixed with the detritus of vegetable and animal matter in different stages of decomposition. In the West Indies, the greatest number of these swamps have a communication with the sea. They are covered with mangrove bushes, to the trunks of which myriads of the mangrove oysters are attached, and they contain also marine animalculæ and small fish, in such abundance as to render the mud upon their surface frequently highly phosphorescent. It is this kind of swamp which, according to Humboldt, contains the constituents necessary to furnish the most virulent species of malaria,―viz. tannin and albumen combined.

By marshy or swampy lands are meant those places subject to occasional inundation, either from the overflowing of a river, from heavy falls of rain, or from any other cause; where, in consequence of their position and the firm and plastic nature of the soil, the water lodges, until carried off by evaporation, and mixes with decayed vegetable and animal remains.

The mud thus formed, when acted upon by the sun's rays, emits vapours deleterious in proportion to the quantity of organic matter which has been mixed up with it and to the activity of the causes which assist in its decomposition. Many countries which under ordinary circumstances may be healthy, become under these fruitful in disease.

In the neighbourhood of Castries we meet with both permanent and occasional swamp, the former being the mangrove fen to the north-east of the town, and the latter is found in all the environs. When both are in full operation, we observe the greatest number of cases of fever: that is when hot and sultry weather has succeeded heavy falls of rain.

During the months of August, September, and October, the heavy showers which are daily occurring in these latitudes are sometimes alone sufficient to inundate the whole surface of a flat country; but when we take into consideration the peculiar formation of St. Lucia, its succession of hill and valley, we must here add another and more important cause to its partial inundation. The waters rush down the steep sides of the mountains, carrying with them the detritus of animal and vegetable life, and cover the plain or valley with a rich, but un

healthy coat of alluvial soil. The river, instead of acting as a drain to the overflooded valley, cannot discharge its own contents, its mouth being blocked up by sandbanks, further strengthened by the fallen trees, shrubs, and earth, carried down from the neighbouring heights. Thus the whole valley is laid under water, which does not retire until the force of the stream has broken through this barrier. In the mean time, the matters contained in the water depose and remain in the form of rich mud and manure upon the surface of the land, which, however valuable it may be to the agriculturist, is exceedingly injurious to his health.

The cultivation of the Anse des Roseaux valley began about thirty-six years ago; since this period not fewer that 800 negroes have been placed or born upon one estate; only 270 remain. The proprietors (two brothers) are notorious for their lenient and kindly dispositions. The work performed by the slaves has always been very inconsiderable, and the annual number of births has averaged sixteen. This decrease in persons who are supposed to withstand the effects of marsh better than any other class of the human race, is terrific. A gentleman establishing an estate in the neighbourhood, purchased, in the year 1802, fourteen African negroes at Dominique: in nine months there was not one remaining. As it is now almost entirely cultivated, it is much less injurious to health than it then was; but even at the present moment very few acclimatized Europeans, or even Creoles of other parts of the island, can long withstand its effects.

The old and permanent swamp just mentioned as adjoining Castries, constitutes the upper extremity of the basin of the Carenage. It was formerly entirely covered by the sea, and is partially so now at high-water. It may, therefore, with some propriety be divided into two portions: that over which the tide continues to flow, and that which, from its higher situation, is no longer exposed to the action of the salt water. The former is thickly studded with mangrove bushes, and contains an immense deposit of decomposed animal matter; the latter is luxuriant with wild canes, guava trees, and logwood, and the proportion of animal matter is less.