ferred to mere medical authority of modern date,) that almost all diseases arise from the air. I believe I may venture to assert, that no writer of any age or country has denied, that the air is a principal cause of epidemic diseases; or that it is alone adequate to produce them. During a plague, which proceeds from a corruption of the air, says Madame Dacier, (Iliad. 1. p. 8.) the sun has not a pure clear light, but is obscured by the grossness of the atmosphere, and by exhalations which ascend like clouds. That the general qualities of the atmosphere are alone quite sufficient to produce epidemic diseases, is farther confirmed by the following, amongst other phænomena, which indicate the approach of pestilence. Moles, mice, serpents, conies, foxes, &c., are observed to quit their subterraneous abodes, and to seek the open air; the birds of the air to depart entirely from their usual residence, as happened in the plague, which afflicted Athens during the Peloponnesian war; and fishes suddenly to die. Calms, as well as the absence of particular winds, and the presence of others, have been observed to be injurious to health. Dr. Baynard remarks, that, during the height of the plague of London, 1665, there was such a general calm and serenity of weather, as if the wind, and the rain also, had been banished the realm; and for many weeks together he could not discover the least breath of wind, so much as to stir a fan. The fires with great difficulty were made to burn; there fell abundance of mildews; and the very birds would pant for breath, especially the larger sort, and were observed to fly more heavily than at other times. (C. R. 1. 73.) Grand Cairo is situated in a sandy plain, at the foot of a mountain, which, by keeping off the winds, makes the heats very stifling. This, with others which I shall afterwards mention, is, no doubt, one of the causes of the frequency and mortality of plague in that devoted city. In a similar manner, the refreshing breezes from the Levant, are intercepted by the high rock of Gibraltar, which occasions stifling heats, previous to the commencement of the epidemic season in that garrison. And this, I apprehend, may serve, at least, in part, to account for the fact, that Gibraltar has been visited with the plague four times in the course of ten years, whilst it has occurred at Malta but once in more than a century. The violence of the winds, as when they are confined in narrow channels, or suddenly turned aside from their course, may readily occasion disease in persons over-heated, or otherwise predisposed. Much depends also upon the points of the compass from whence they blow. Of the winds in our hemisphere, generally speaking, the wholesome seem to be the Etesian, or those which blow from the North, and the unwholesome those which blow from the South. According to Frederick Hoffman, manufacturers of nitre have observed, "that the beds of earth prepared for that acid of the air, which constitutes the very essence of the nitre, are impregnated principally or solely, whilst the winds blow from the points of the compass between the North and East." (Ingr. 64.) These winds are remarkable for cooling the air. In Egypt the Etesian winds are said generally to prevail at the period of the overflowing of the Nile, which is also the period of the cessation of the plague in that country. (Ing. 65.) Hippocrates, and other ancient Physicians, have insisted especially upon the noxious qualities of the winds which blow from the South Celsus, after giving some directions respecting what ought to be avoided during an epidemic, adds: "all these things ought to be attended to in every pestilence; but particularly in that which is brought on by Southerly winds." Lancisi states, that Varro being at Corcyra whilst a fleet and an army were there, and all the houses were filled with the sick and the dead, made new windows on the opposite side of the house, and admitted the North wind, shut up the pestilential light on the other side, and changed the door, by which, and other attentions of a similar nature, he carried his companions and his family safe through. Empedocles is said to have delivered his country (Sicily) from barrenness and from pestilence, by closing up, as Plutarch relates, an opening in a mountain, through which the south wind used to blow upon the plains. According to the same principles, the absence of the Etesian winds ought to be noxious, and the Southerly winds salutary. And we find that the Etesian winds not blowing as usual that year, is assigned by Diodorus Siculus, as one of the causes of the great plague of Athens. In Egypt, are the Etesian winds absent, or do Southerly winds prevail, previous to, or during the periods of pestilence? The qualities of the atmosphere must, no doubt, frequently be determined by the nature of the soil, which we inhabit, or over which the winds blow. Impregnated from salt petre grounds, as in the East Indies, they will occasion convulsive, and spasmodic affections, paralysis, tetanus, fever, cholera morbus, and death. After a course of Southerly winds, blowing over the burning sands of Africa, a plague very often follows at Tunis, during which the inhabitants withdraw to old Carthage. When epidemics prevail in the towns, on the coast of Africa generally, in Gibraltar, and other parts of the Peninsula, and at Malta, in the same season, they usually commence, spread, decline, and cease, in all of them, at periods nearly, or entirely similar. The atmosphere notoriously becomes noxious to health by impregnation with marsh effluvia. Among the ancients it was no uncommon thing to introduce pure water from the hills, to correct the malignity of marshes. We read in Strabo, that the marshes near Alexandria lost all their mischievous influence, when they were overflowed by the Nile. It still continues to be at the precise. period, at which the slimy bed of that river becomes exposed, that the plague commences, and when it is again covered, that it ceases generally in Egypt. Through the midst of Grand Cairo, there passes a great canal, which is filled as the waters of the Nile increase, and emptied as they diminish. It is at the latter period that the plague commences, and at the former, that it ceases in that city. In the Island of Zealand, which is full of stagnant waters, there occurs an epidemic intermittent, almost annually, in the autumn. That the epidemics of Gibraltar, where there are no marshes, should commence, spread, decline, and cease, at precisely similar periods, shews, that these diseases obey similar general laws, and that it is the type only, which is determined by the modification of the cause. When the Salopians of the Lake were annually visited by a pestilence, M. Hostilius freed them from it by removing them four miles from the place. Formerly the city of Oxford was unhealthy, the Isis and Charwell being filled with mud, from which after a flood, noxious exhalations ascended. In 1517, at the charge of Richard Fox, Bishop of Winchester, those rivers were cleansed, and more trenches cut for the passage of the water, since which time the town has been more healthy. Empedocles delivered the Selinantic from a pestilence, by directing two neighboring streams to be turned into the Lazyore, a sluggish stream crossing through their settlement. By this operation, its course was rendered more brisk, the channel was cleansed, and, as Laertius relates, the waters becoming fresh and sweet, the plague ceased. Peter Salius Diversus, in his tract upon pestilential fevers, has the following observations: "If pestilential fevers proceed from stagnant waters, the first thing to be done, is to introduce a runing stream; or else to dry them up altogether, as is practised in my country, where the water stagnated in the public canals round about, and undergoing corruption, excited, towards the end of summer and during the autumn of every year, violent pesti lential fevers." In another place he states, that, "no sooner were ditches, in the vicinity of his residence emitting a bad smell, filled up, than the inhabitants were most happily freed from the pestilential fevers, by which they had, for many years, been harrassed about the close of the summer." Diodorus Siculus ascribes the plague of Athens to the following causes "abundance of rain had fallen in the winter, by reason whereof the earth being over wet in many places, especially in low and hollow grounds, the water lay like standing pools, and those being putrified and corrupted by the heat of the summer, thence produced a mist of gross and stinking vapors, which corrupted the air, as it often happens about filthy marshes; and besides the want of food much advanced the progress of the disease; for the year before, the fruits, by too much rain, were crude and unwholesome.” In the harbors especially of woody and uncultivated countries, the health of the crews of ships, will depend very much upon their sleeping on board, or on shore, upon their being exposed to the sea, or to the land wind, and upon their proximity to, or distance from the shore. A few cable lengths may in this respect, make a very material difference. The farther from land, the more security, the nearer, the more danger. In respect to my present object, it would be superfluous to enlarge upon the manner in which the qualities of the atmospheric air may be effected by earthquakes, minerals, metals, salts, volcanos, comets, or planetary influence. Neither is it material to inquire particulary into the effects of vegetable exhalation, and animal putrefaction, meaning to indicate, rather than to explain the causes which vitiate the atmosphere, so as to occasion epidemic dis eases. There is, however, one cause, which, as it did not operate to so great a degree in ancient, as it has done in modern times, has been considerably overlooked, and is so frequently in action, and of such extensive influence, as to occasion several of our principal and most usual epidemics, seems to deserve more particular conside ration. I mean that alteration of the qualities of the air, produced by the breathing of many persons, confined together in a small space, which is always a principal, and often the sole cause of those modifications of Typhus, called Hospital, Ship, and Jail fevers, so common in this country. The effects of a noxious atmosphere, produced by respiration, operating in various degress of intensity, are well exemplified by the great diversity of phænomena, which marked the memorable catastrophe of the English factory imprisoned in the black hole of Calcutta, as described in the narrative of Mr. Howell. Formerly, in the jail of Newgate a fever used to appear annually, but only in hot weather. (Ing. 103.) But the injurious effects of the air of jails have been manifested in their most destructive, as well as most edifying form, when the apartments over them (it was formerly the custom in this country to have the prisons, or dungeons, immediately under the place of trial) have been opened for the purpose of holding the Assizes. The foul air of the prison underneath, together with the noxious vapors of the cold and damp apartments newly opened, being set in motion, and being driven by currents of the external atmosphere against the auditory, affected them so as to produce fatal maladies; whilst the prisoners, who were habituated to that foul air within, and less exposed to the currents from without by which it was set in motion, escaped unhurt. This I apprehend will be found to be the proper explanation of the memorable affair of the black assizes at Oxford in 1577, when the judges and the auditory, to the number of three hundred, were seized with a malady, of which they all, or almost all, perished, whilst the prisoners remained uninjured. It is stated that "almost every one present died within forty hours." A similar calamity is stated to have taken place at Oxford in July, 1579. The jurors died presently; shortly after died Sir Robert Bell, Lord Chief Baron, Sir Robert de Olie, Sir William Babington, Mr. Winman, Mr. De Olie, High Sheriff, Mr. Davers, Mr. Harcourt, Mr. Kisle, Mr. Pholeplace, Mr. Greenwood, Mr. Foster, Serjeant Baram, Mr. Stephens, &c. There died at Oxford three hundred persons; sickened there, and died at other places, two hundred and odd from July 6 to August 12, after which not one died of that sickness. (Tell Tale 194.) In 1581 Mr. Teegion at Lawnston, Mr. Rigby, Mr. Christopher Watson, with eighteen persons more (popish priests), perished at York with the disease of the prison. (Jews and Babel, p. 549.) At an Old Bailey Sessions in 1750, in the mayoralty of Sir Samuel Pennant, Sir Thomas Abney, Mr. Baron Clark, the Lord Mayor, Mr. Daniel Lambert, half the jury, Mr. Anthony Biggs, Surgeon, and many others, lost their lives. About the middle of the last century many persons being close shut up in the prison of St. Martin's round house, some died in a few hours. In my work upon epidemic diseases I have stated instances of ship-fever, or typhus, produced simply by shutting down the hatches, and keeping prisoners confined in a small space without ventilation. On board of Guineamen both fever and scurvy have frequently been occasioned in this manner. That the alteration produced in the air by the respiration of Pam. L |