rous predisposing or auxiliary causes concurring to enable the original to develope itself. If we take the medium of these two extremes, we shall have the ordinary period, viz. twelve or fourteen days, which elapses between the reception of vegeto-animal miasmata into the body, and their manifestation, in the shape of actual disease.

We see, then, this important agent greatly varying in force; and from standing occasionally the unaided principal,- the "instar omnium," in the production of fever, dwindle away till it can scarcely be distinguished, at least not prominently so, among the train of auxiliaries.

Such being the case, is it not probable that where the latter are numerous or powerful, they may, in some instances induce the aforesaid disease, without the assistance of marsh exhalation ?-See a valuable train of observations on this subject, in the Section on Yellow Fever of the West Indies, in a subsequent part of this work.

PREDISPOSING CAUSES.

We now come to the predisposing causes, which are entitled to an equal degree of attention with that which has been bestowed on the remote, or exciting.

These may be divided into mental and corporeal. Of the former, none are so conspicuous as the depressing passions; and of these Dr. Clarke informs us that FEAR produced the most striking and sudden effects, in aiding the remote cause of fever. This may, in some measure, account for the ravages which the yellow fever commits among those newly arrived Europeans, who are prepossessed with the idea and dread of this terrible scourge.

I have, indeed, remarked that most of those, who were of a timid disposition, and easily alarmed at the prevalence of the endemic diseases of the country, fell under their influence sooner than those of a contrary temperament. But grief, disappointment, and chagrin were the depressing passions which universally induced the most decided and unequivocal predisposition to disease. I saw many strong and melancholy instances of this among that part of our crew, which we impressed within sight of their own shores, and probably of their own habitations, when we were commencing our voyage to India. They were among the first and worst cases which I had under my care, and afforded ample proofs, that mental despondency can accelerate the attack, and render difficult the cure of intertropical fevers in particular. I have since seen the influence of this predisposing cause on a large scale ;-not on the banks of the Ganges, but much nearer home-on the banks of the Scheldt.

When our army lay entrenched under the walls of Flushing, without any other defence from the sun, the rains, and the dews, than some brushwood or straw ;-generally, indeed, with the humid earth for their beds and the canopy of heaven for their curtains; still, with all these disadvantages, the animating prospect of success, the mental energy inspired by hope, united with corporeal activity, kept the whole army in health. When Flushing surrendered, however.

and another object was not instantly held out for pursuit or attainment, a fatal pause took place, and a kind of torpor, or rather exhaustion ensued, during which, the remote cause of fever, viz. vegeto-animal miasmata, began to make some impression. But when from the ramparts of Batz, we clearly discover with our glasses a strong boom crossing the Scheldt from Fort Lillo,-the surrounding country in a state of inundation, and various other insuperable obsta cles between us and the " ulterior objects" of the expedition;-then, indeed, the depressing passions, and some other predisposing or exciting causes communicated a fearful activity to marsh effluvium, which rivalled in its effects, any thing that has been seen in tropical climates !

It is an old complaint, that the medical topography, and healthy or unhealthy seasons of a country, are too often neglected in military and naval operations. Yet one would suppose that within sixteen or eighteen hours' communication of London, every medical and political expedient would have been speedily devised and applied, on such an emergency as this. But certain it is, that the army did not avail itself of some local advantages that presented themselves among these noxious islands. Walcheren, for instance, is bounded all the way round from Flushing by West Chapel, nearly to camp Vere-twothirds of its circumference, by a chain of sand hills, from twenty to thirty feet in elevation above the level of the interjacent plains. These hills were not only dry, but open to the westernly winds which blew from the sea, and were then very prevalent. On these, therefore, had the soldiers, who continued in Walcheren after the fall of Flushing, been tented, the elevated site, combining with other local peculiarities, would in all probability, have kept them entirely out of the range of those exhalations which covered the country below.

On the other hand, although Beveland did not present such a favourable situation to the rest of the army, yet had they been provided with tents, the numerous mounds or embankments, which not only defend the island from the highest rise of the Scheldt, but intersect the country in every possible direction, frequently planted on each side with trees, and raised twelve or fourteen feet above the surface of the soil, would have afforded excellent encampments, where the men under the immediate inspection of their officers, would have been secured from intemperance and other irregularities, the inevitable consequences of being quartered in towns and villages, often in churches, barns, and other damp, unhealthy habitations throughout Walcheren and Beveland. But unfortunately, tents were not considered a necessary part of the baggage on this expedition. The French general, too, having opened the sluices, and partially inundated the country round Flushing, increased the force of the endemic. Indeed, the road leading from the last mentioned place to Middleburgh, might at this time vie, in respect to insalubrity, with any through the pontine fens of Italy. Lenity towards the inhabitants arrested the progress of the inundation before it was complete; policy in guarding the health of our own army, would perhaps have suffered it to continue

n'

till the cessation of the autumnal heats, and the commencement of cold weather and frost.

Nothing could more clearly prove the limited range of marsh effluvium, than the contrast between the health of the navy and that of the army. Although the ships were distributed all along the shores of Walcheren and Beveland, from Fushing to Batz, most of them within a cable's length of the banks, yet no sickness occurred, except among such parts of the crews as were much employed on shore, and remained there during the nights. Most officers of ships, and many of the men, were in the habit of making excursions through all parts of the islands by day, with complete immunity from fever. The night was here, as in sultry climates, the period of danger.

One more remark shall close this digression. We all remember the popular, or rather political outcry, that was made about the scarcity of bark had the lancet, aided by calomel, and occasionally by jalap, been judiciously, but boldly and decisively employed, the physicians of London and Edinburgh would not perhaps, since that period have been so often consulted for infarctions and obstructions in the liver and spleen, with many other melancholy sequela of that destructive fever!

But to return. One would suppose that in a tropical climate, where nature is ever arrayed in her gayest livery, the cloudless skies above, and exuberant fertility around, would conspire to impart a degree of elasticity, (if I am allowed the term,) and exhilaration to the mind, similar to what we feel in Europe, at the approach of spring or summer. The reverse of this is the case. The animal spirits are in general, below par; and the same cause of grief or disappointment,which in England would be borne with philosophical resignation, or perhaps indifference, will, in India, greatly predispose to all the diseases of the country, and very probably terminate the mortal career of the unhappy object.

The following melancholy facts are strikingly illustrative of this remark. His Majesty's ship Pussel, (74,) sailed from Madras on the 22d October, 1806, and arrived at Batavia on the 27th November; the crew healthy, and their minds highly elated with the sanguine expectations of surprising the Dutch squadron there. Such, however, was their sudden disappointment, and concomitant mental dejection, on missing the object of their hopes, that they began immediately to fall ill, ten, twelve, or fourteen, per day, till early 200 men were laid up with scurvy, scorbutic fluxes, and hepatic complaints! Of these, upwards of 30 died before they got back to Bombay, and more than 50 were sent to the hospital there. The Albion did not fare better-the Powerful fared worse: so that, in these three ships only, in the short space of a few months, full one hundred men died on board, and double that number were sent to hospitals, many of whom afterwards fell victims to the diseases specified; aggravated, and in a great measure engendered, by mental despondency.

Numerous are the instances of a similar nature, though on a smaller scale, which I could relate; but the above specimen is sufficient.

See page 58

The converse of this position is equally surprising: thus, success or good fortune will as forcibly counteract, as the contrary will predispose to, the malignant effects of climate. A familiar example will elucidate this.-Two ships, under equal circumstances, sail from Bombay, on a five months' cruise off the Isle of France, One of them takes a valuable prize, while the other, with every effort and vigilance, is quite unsuccessful. The minds of the former crew are now perpetually employed in " building castles in the air," and forming the most extravagant anticipations of enjoyment on their return to port. The ship's company, without the aid of a single bottle of lime juice, or pot of spruce, will come back to Bombay at the end of the cruise in health. Not so the other : chagrin, envy, (for, after all the poetical portraits that are drawn of our noble tars, they are both envious and jealous at times, like other folks,) and various depressing passions, show themselves here, in the ugly shapes of scurvy, ulcers, and fluxes; so that, in spite of all the artificial checks from lemon juice, sugar, porter, and even NOPAL itself, they are forced to Madagascar for refreshments, or else return with the other ship to Bombay, in a deplorable condition.

Here, however, the scene shifts again; for Hygeia is as fickle as Fortuna. The crew of the successful ship having shared their prize-money,

"Balnea--Vina-Venus,"

become the order of the day; and, for a short time, they are at the summit of human happiness! But in a few weeks, on leaving port, this ship's company will exhibit as long a list of tevers, dysenteries, and venereals, as the other did of scurvies, ulcers, and fluxes, on arriving. Thus prize-money, or rather the hope of prize-money, is one of the most potent antidotes to disease among sailors at sea, but the most certain bane of their health on shore.

To return. This mental despondency may be attributed partly to physical, and partly to moral causes. I have already hinted that derangements in the hepatic and digestive, very soon affect the mental functions; so, on the other hand, the depressing passions speedily derange the biliary secretion, digestion, and peristaltic motion of the intestines, consequently disposing the liver, stomach, and alimentary canal, to disease, as well as inducing general debility throughout the system. This sufficiently accounts for the phænomenon; but it is also to be considered, that grief and disappointment must be, cæteris paribus, more poignant in India than in England; since the loss of friends or relatives are more felt in proportion to the small number we possess; and frustrated expectations will, of course, be more galling on account of the previous sanguine bopes which always accompany a foreign, and particularly an Indian speculation We may therefore lay it down as an axiom, that in a tropical climate, the depressing passions above alluded to operate more immediately on those organs which, under all circumstances, are the principal sufferers in the diseases of the country; viz. that they diminish the mental energies, or sensorial power, and impair the functions of the liver, stomach, and intestinal canal.

Within the torrid zone, philosophy seems to direct her influence, and reason its arguments, in vain, against these powerful disorders of the mind! Their frigid tenets are more efficacious beneath the gloomy skies of Europe. Religion, indeed, frequently asserts her superiority here, as well as elsewhere; and in conjunction with some pursuit or employment, mental or corporeal, will be found the best shield against the demon of despair, and, ultimately, the pangs of disease.

The destructive effects of intemperance, as a predisposing cause, are equally conspicuous, and I might say peculiar, in a tropical climate; for the injuries it occasions in Europe, great as they are, bear no proportion to those which we witness in the East or West Indies. Whether spiritous and vinous potations act as stimulants or sedatives, or both in succession, we need not stop to inquire, since the final result is universally allowed to be debility. From the temporary increase of excitement in the system, and energy in the circulation, it is not impossible that the biliary secretion is for a short time augmented, and of course vitiated, by strong drink. This supposition is strengthened by the diarrhoea crapulosa which we frequently observe succeeding a debauch. But the great mischief seems to arise from the torpor communicated to the liver, through paralysis of its ducts, by which the secretion of healthy bile is not only greatly diminished in quantity, as well as obstructed, but deteriorated in quality; and hence the way is paved for fever, dysentery, and hepatitis.

The debility of the stomach, too, occasioned by the climate, is further increased by inebriety; and this atony is readily communicated to the liver, which bears the onus of disease in all hot climates. The truth of these observations is amply exemplified among the crews of ships, when they have liberty to spend a few days at Calcutta, or go ashore, indeed, in any part of India, where intoxicating liquors are to be procured. During the indirect debility succeeding these debauches, the endemic of the country or port makes rapid strides among these deluded victims, converting what they erroneously conceived an indulgence, into the greatest evil that could have befallen them.

For obvious reasons, intemperance in eating is little less destructive than the other species; since an overloaded stomach, which has previously been weakened, will of itself excite a temporary fever, and consequently predispose to that of the country.

That fatigue, especially during the heat of the day, becomes an exciting cause of this fever, is well known to those who have observed its effects among the seamen employed in stowing the saltpetre, or loading and unloading the company's ships at Diamond Harbour. Where those laborious occupations must be carried on by Europeans, they certainly should not take place between eleven o'clock and four in the afternoon; the interval ought to be dedicated to dinner, rest, and light work under the awnings.

A very common, and powerfully predisposing cause of this fever, has seldom been adverted to, though highly deserving of attention -I mean those licentious indulgences which are but too easily pro