"The Chinese, however, who are very numerous, suffer more than any class of the people; perhaps, from the worse situations of their houses, the manner in which these are crowded, the closeness of their apartments, and their gross manner of living. The number of casualties among them, I am told, is incredible, especially during the dry season; and if one may judge from the extent of their burial ground, and the number of their tumuli, it cannot admit of a doubt. The preceding facts are, I conclude, sufficient to establish the truth of the noxious character the climate of Batavia has so long obtained, and I shall now proceed to the causes which have been often investigated, and seem well ascertained, though the knowledge of them has led to little exertion for their removal.
"The baneful effects of marsh miasmata on the human system is well known, engendering intermittent and remittent fevers, dysenteries, and visceral obstructions. Batavia, built almost in a swamp, surrounded by marshes in all directions, trees and jungles, which prevent the exhalations being carried off by a free circulation of air, is peculiarly obnoxious from this cause. Opposite the mouth of the river, and extending a great way to the westward, is a mud-bank, which, in many parts at low water, is uncovered by the sea, and is daily accumulating from the quantities of mud and animal and vegetable matter carried down by the river during its reflux. Again the sea, often at spring tides, overflows the adjacent country, and, on its receding, leaves the soil covered with slime and mud, which, exposed to the action of the sun, soon suffers decomposition, and impregnates the atmosphere with its noxious exhalations, which are carried by the sea breeze over Batavia, where the trees and jungles surrounding the houses prevent their being dissipated. During the heat of the day these exhalations are more diffused and comparatively innoxious, but when the sun withdraws its influence they become more condensed, and amalgamating with the descending evening dews form a morbid atmosphere around the houses of the inhabitants. This hypothesis will readily account for a fact well known, that people whose commercial concerns require their presence in Batavia during the day, and who retire during the night into the country, escape this endemic, while scarcely any who sleep in the town, even for a night, unless those who, by a long residence, are inured to it, escape. In the ingenious and sensible work formerly alluded to (Mr. Johnson's), I find this hypothesis so clearly and perspicuously expounded, that I must take the liberty of quoting it.
"'The cause why the stench emitted by marshes and vegetable matter in a state of decomposition is more perceptible immediately after sunset, is not that the vapours are disengaged in greater quantities then than during the day, but the marshes retain their heat for some time after the sun's rays are withdrawn, and consequently continue to emit vapours through the atmosphere, as during the high temperature of the day by the sun. They therefore meet the descending dews, condensing and forming a thick fog, which hovers over the swamps, accompanied by a noxious and disagreeable odour. The miasmata exhaled during the day, in all probability, descend with the dews of the evening, which, meeting and combining with those that continue to be disengaged from their source, must form a concentration highly capable of affecting the constitution. Marsh effluvia become at a certain distance from their source innoxious. Dr. Hunter observes, 'a few feet in height gives a comparative security in the same buildings.' This will be accounted for by the supposition, that as the miasmata exhaled during the day descend in the evenings, they become more and more concentrated, till meeting the exhalations from the still reeking marshes, a dense stratum of highly impregnated atmosphere is found contiguous to the surface of the earth: hence the salubrity of sleeping in upper apartments. This leads to another practicable inference of considerable importance, that when necessity compels exposure to these marshes, we should select that point of time least likely to meet those miasmata, whether ascending or descending. This period seems to extend from three to six in the afternoon:[282] that is, after the greatest heat of the earth and air, and consequently the greatest evaporation, and before the condensation and return of such exhalations as rose during the day, and which combine with those still issuing from the heated soil for some time after sunset.'
"A second, and, I think, an equally powerful cause, is the stagnant water of the canals, which, in all directions, intersect the city. In the first place, they are filled with filth of every description; there is scarcely at times any perceptible current in them to carry off that filth; and lastly, the sluices are frequently kept shut, for the purpose of swelling the waters above them to irrigate the fields, while those below, which intersect the town, become almost dry, leaving an extensive surface of mud, and every kind of putrified matter, to be acted upon by the sun, raising the most pestilential vapours, with which, as before observed, the atmosphere gets thoroughly impregnated.
"As a third cause, the state of the houses may be considered, and the mode of living of the Dutch. Houses that are untenanted are seldom opened, and thus collect much filth and foul, damp, pernicious vapours. Those that are inhabited are generally shut up in the day time, most of them being glazed, thus preventing a free circulation of air; and in the lower story of most of the houses, the walls are covered some feet from the ground with a greenish coat, and on entering the apartments a stranger experiences a kind of chilly feel, and a damp raw kind of smell. Although it cannot be enumerated among the causes, yet I cannot help thinking the Dutch mode of medical practice, in as far as it is inefficient to counteract the diseases of this climate, must tend to increase the number of fatal terminations.
"The Dutch practitioners, little in the habit of theorizing, continue the same practice in every form of disease, and they are particularly prejudiced against the use of mercury, opium, and other powerful medicines, in consequence relying solely on the most simple and inert remedies. Some few of them, of more enlarged understanding, adopt the English mode, and seem sensible of its superior efficacy.
"A fourth, and, I am convinced, a very general cause, especially of the diarrhœas and dysenteries, which seldom fail to attack new comers, is the water. This most essential article is taken either from the canals or wells, and it is equally bad when passed through a filtering stone. It retains a brackish, hard, unpleasant taste, and if allowed to remain some time in vessels without previous boiling, generates small animalculæ. Such, I conceive, are the most probable and principal causes of the insalubrity of Batavia; though there are, I doubt not, others contributing, which elude observation. It is generally received, though I think an erroneous opinion, that the rainy season is the most unhealthy. The most unhealthy appears to me to be that immediately after the cessation of the rains; and the older and more experienced Dutch residents have observed, that in years when there has been a long continued drought, disease has been more than usually prevalent, and they look forward with anxiety for the accession of the rains, as the means of resisting its baneful dissemination.
"Weltevreden, at a distance of not more than three miles, being less exposed to these causes, excepting the water, is exempt, in a great measure, from its prevailing endemic fever; though diarrhœas are common, especially among those newly arriving, but they are seldom of a serious or alarming nature.
"Among the troops stationed at Weltevreden and Cornelis, diseases are not more frequent than in the healthiest parts of India which I have visited; though for some months since the Báli expedition, the casualties in the 78th regiment have been numerous. At Chemangis, about twenty-two miles from Batavia inland, a battalion of Sepoys is stationed, where, from the returns I have received, it appears they enjoy comparatively good health, and have very few casualties, though a much larger quantity of rain falls than in the vicinity of Weltevreden. It is on an elevated commanding situation, and open and clear of jungle for a considerable extent around."
In support of the opinion which has been given of the general salubrity of the climate of Java, the abstract returns of sick, &c. among the troops serving on Java and its dependencies, for the last two years, are annexed, together with a statement of casualties, in His Majesty's 78th regiment, while serving on the continent of India and in Java.