SECTION XIV.

MEDICINE AND MEDICAL
STATISTICS.

BY ALEXANDER BRYSON, Esq., M.D.

It will necessarily happen, from the great proportion of the naval force employed on foreign stations, that amongst the first things which will attract the attention of a medical officer, are the effects produced on the constitution by a change of climate; and the question of the necessity or non-necessity of meeting this change by an alteration of personal habits or modes of living; whether on entering the tropics it will be prudent to continue the use of the same daily amount of food, to lessen its quantity, or to adopt a diet less stimulant as regards fluids, and more farinaceous as regards solids. Different views have been adopted on this subject, some of them erroneous, others extravagant, or only feasible were the human body a mere machine; while there is a third class founded on practical experience, and which is deserving of the most respectful consideration. Opportunities to simplify and reduce these into a more intelligible form will not be found wanting in the naval service.

In noting the meteoric changes which are likely to

affect health, there are not, it may be assumed, any great difficulties to be encountered as regards instrumental observation; mathematical precision, at all events, is not so essential as it would be, were the results aimed at depending on the truth of a series of arithmetical sums. There is, nevertheless, a proper degree of accuracy required in the mere registration of this kind of formulæ, as one omission may invalidate a whole set of observations-such for example as the geographical position of the ship at the time the observations were made.

With regard to the atmosphere, the principal things to be observed are its heat, degree of humidity, and weight. That the two first greatly influence health there is not any reason to doubt; but with regard to the third, it would be hazardous to offer any decided opinion. Amongst men who have devoted much of their time and attention to the subject, there are perhaps a few who consider that it has at least some influence in disturbing occasionally the equanimity of the mental functions. Thermometrical observations with the view of noticing the influence of atmospherical heat on health, should be made several times a day, in order that the minimum, medium, and maximum in the shade may be ascertained; or even more frequently should there be a sudden rise or fall of the mercury. On board a ship under way, it is hardly possible, in consequence of the great variety of aspects in which she may be placed with respect to the sun, and the various currents of air rushing from her lower deck, to find a suitable place for the instrument; the black bulwarks and hammock-cloths rapidly absorb the heat of the sun's rays, and again throw it out by radiation

for a considerable time even after the sun has gone down. Should the instrument therefore be placed, as has sometimes happened, contiguous to these, it will give an exaggerated view of the temperature. The under surface of the deck planks also radiates heat abundantly after the upper surface has been long exposed to the rays of the sun, consequently the temperature of the cabins and between the decks of a ship is sometimes greatly increased; this, however, if continuous in apposition with the heat in the sun's rays, and in the shade, it would be desirable to place on record, and also to state the influence it may be supposed to have on the general health of a ship's company, whether the inference drawn be of a practical or a theoretical nature. In connexion with accumulated heat from these or other causes, it would also be proper to state the space allowed to each hammock; the number of hammocks berthed on one deck, and in a general way the dimensions of the deck, together with the size and disposition of the scuttles, ports, and windsails.

Acute inflammatory diseases and fevers have most unquestionably been induced by a current of external air rushing in through a scuttle or from the lower orifice of a windsail on men while asleep. Are we then to suppose, in the absence of all terrestrial miasmata, that these diseases are the result of the sudden abstraction of heat from the system? Simple immersion in the sea, or exposure to the external air in a state of nudity, has not, generally speaking, to the same extent, an equally deleterious effect.

These, and subjects of a like nature, are well deserving the attention of every medical inquirer; as

there are few of the doctrines respecting the origin of disease, or the manner in which the different forms of morbid action (when once established) progress, culminate, and decline, that are yet so clearly demonstrable as could be wished.

As a humid state of the atmosphere, particularly within the tropics, seems to exercise a considerable influence over the health of Europeans, hygrometrical observations are not less essential than thermometrical, to a full investigation into the causes and nature of any of those diseases usually denominated climatorial. Various instruments have been used for these purposes; but those which denote with ordinary accuracy the state of the atmosphere, and are the least liable to get out of repair, are the best. The appearance of surrounding objects and our ordinary sensations may be even trusted where there are no better means at hand. It will naturally occur to the observer to guard against confounding the moisture arising from any local cause, such as damp decks, or the halitus from the breath of a large body of men confined in a small space, with the natural moisture of the external air. Should the disparity, however, between the latter and the air of the deck on which the men generally congregate and sleep, be great, it will be incumbent on him when he uses an instrument to note the difference. From these data, viewed in connexion with the results of the thermometer, the necessity of a more free ventilation in all vessels of war destined to remain for years within the humid regions of the tropics may thus be made apparent.

To a dry air we are accustomed to attribute a bracing effect, to a moist air a relaxing; and there seems

to be little reason to doubt the general truth of the postulate; the first increases, and the second diminishes the amount of watery fluid in the system; the one as a general rule conduces to health, the other to disease. How far these conditions modify morbid action, it would be desirable to ascertain. That intermittent and remittent fevers are the peculiar product of moist localities, experience amply proves; and although the subject yet requires to be more fully examined, facts are not wanting to lead to the supposition that dysentery, and diarrhoea approaching to dysentery, are more frequently the result of atmospheric changes in certain dry localities within the tropics, than they are in moist localities in similar parallels of latitude.

The relative degrees of health enjoyed in vessels differing in the hygrometrical condition of the air between decks, from whatever cause (exclusive of external causes) such differences may arise, is a subject which has long engaged the attention of all classes of naval officers; and although the majority are of opinion that a dry condition is the more healthy, still there are others practically acquainted with the subject, who do not admit that the difference is appreciable, or who altogether repudiate the idea of damp decks having anything whatever to do with the health of a ship's company. As these conditions greatly depend on the modes of cleaning the lower decks, it more especially belongs to the medical officers to watch with vigilance, and report (but not without due and ample experience) the effects of dampness, whether arising from accident, stress of weather;—or, artificially produced; as well as the effects of dryness artificially maintained by swinging stoves or other contrivances.