many patients crowded together in an hospital, especially if the building be in a low or unwholesome situation, will be followed, when in a sufficient degree, with fever of a similar description, requires neither proof nor illustration.

2. Sudden or Extreme Vicissitudes of Temperature.

The second cause of epidemic diseases, which I have enumerated, is sudden or extreme vicissitudes of temperature. It cannot be doubted, that this is a sufficient cause of disease, nor that, when extensively operating, it is capable of occasioning an epidemic. It, however, for the most part, only acts as an auxiliary or collateral cause: the countries in which those vicissitudes are the greatest, and the seasons in which they are the most extreme, will be found, other things being equal to be the most subject to epidemics. In Egypt, the variation of the thermometer from noon to midnight, in epidemic seasons, is stated to be usually very great. At Malta in 1813 it was when the difference between the temperature of noon and midnight was at the highest, that the plague was the most extended, and the mortality the greatest. In individuals it is about midnight, or towards morning, that attacks of disease, as well as death, are believed most frequently to happen. This is the period of the twenty-four hours which constitute the day, at which the diminution of temperature is the greatest, the air which we breathe the least pure, and the exciting powers, generally, both physical and moral, applied in the smallest degree of intensity.

3. Deficiency of Nourishment.

It is notorious, not only that years of famine, arising from actual scarcity, are also years of pestilence, but that, in every community, those classes or individuals who have the fewest means of procuring subsistence, are also the most liable to epidemic maladies. And, if a deficiency of nourishment should not be deemed alone an adequate cause of pestilence, there cannot be a doubt that it will often be sufficient to produce the disease, when, from the force of the other causes merely, it would not take place.

One of the causes of the plague of Athens, according to Diodorus Siculus, was a scarcity of food.

In the year 21 before Christ, the plague of Syracuse was preceded, and seems to have been principally occasioned by famine.

In England a famine commenced in 1315, which was so great that horses and dogs were eaten, and continued for three years, énding in a most terrible pestilence.

During the plagues of London in 1665, and of Marseilles in 1720, a scarcity of provisions was occasioned by the mistaken

measures which were resorted to, in consequence of the belief in contagion, with a view to prevent the spreading of the malady; and the scarcity, in its turn, greatly extended both the sickness and mortality.

4. Depression of Mind.

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The last of the proper causes of epidemic diseases, and a very powerful one, is terror, or a settled depression of mind. Lancisi, (chapter vii and xviii) places serenity of mind among the requisites in his prophylactic plan. "I do not, however," says he, commend cheerfulness as an antitode to pestilential distempers upon theoretical considerations alone, but I do so upon the solid basis of experience, and request my readers to note it accordingly. Rivinus and others have related, that during the prevalence of plague, fear wrought greater mischief than the true contagion itself; on which account he solemnly declares that, during the plague at Leipsic in 1680, he did not know a single instance of sickness occurring from the plague, which did not originate in terror. And yet this observer saw numberless cases of the disease in Leipsic. The subject may be illustrated by the experience of my late colleagues John Mana Constance, and Luke Tomasino, during the pestilence which almost depopulated Rome in 1655. Those physicians personally attended the sick in the plague hospital, and frankly owned to me, that their escape from that violent contagion was owing to their firm and cheerful state of mind, enabling them to disregard death, and administer friendly reproof to the fearful. All those who were timid were carried off by the distemper."

These are the statements of persons believing in contagion ; and yet it is self-evident that neither can the greatest equanimity prevent, nor the greatest timidity occasion, a disease, which depends upon contagion, although the former may serve to mitigate, and the latter to aggravate its effects. Fearlessness cannot prevent, nor terror occasion small-pox.

On the other hand, under a slight degree of epidemic constitution of the air, and of deficiency of nourishment, terror might occasion disease, when it would not otherwise happen; and, under a higher degree of those causes, equanimity might prevent disease, when it would otherwise take place. It is to this source (equanimity), rather than to his strict temperance, as reported by Aulus Gellius, that we ought probably to attribute the exemption of Socrates from the plague, which in his time afflicted Athens.

Noxious qualities of the air, then, sudden or extreme vicissitudes of temperature, deficiency of nourishment, and depression of mind, constitute, what I consider, the four proper causes of pestilence;

which, in their various combinations, proportions, and degrees, produce every known species of epidemic. The first is undoubtedly the chief, and sometimes at the commencement, the sole cause. But it is, for the most part, at least in the progress of epidemics, united with one or more, or all the other causes; and one or more, or all the other causes, may, in the absence of the noxious qualities of the air, be adequate to produce disease. Upon the variety of their combinations depend the modifications of disease produced.

SECTION V.

Adventitious Causes of Epidemic Diseases.

The consequences of the belief in contagion considered as a cause of epidemic diseases, by adding to the force of the proper causes, greatly multiply, in all severe epidemics, the otherwise inevitable sickness and mortality.

The terror inspired during a pestilence, by the view of sur rounding calamity, and by the apprehensions, whatever be its presumed cause, of being affected like others, forms an additional, and perhaps the most powerful cause of mortality. But under the belief in contagion the disease is deemed almost inevitable, and terror is still farther increased: and when that opinion, sanctioned by medical authority, is accredited by governments and municipal bodies, and officially acted upon by the adoption of conformable measures of police, with a view of prevention, the panic is augmented in a dreadful ratio, the public mind is appalled, and destruction becomes incalculable. Under such circumstances the very rumor of a pestilence in any one quarter of the globe spreads universal alarm, and begets universal precaution in every other; and, in the progress of an epidemic, affecting several countries, the inhabitants of the most remote quarters from the scene of its commencement feel its baneful influence long before its approach. A plague, or yellow fever, occurring in Asia, Africa, or America, will occasion the adoption of the most rigid quarantine on the shores of the Baltic. The arrival of a ship or vessel from any country, in which pestilence frequently occurs, is attended with precautions, even when there is no actual disease either in the vessel herself, or in the country from whence she came. And when there happens to be actual disease on board, or at the port which she had left, and an epidemic simultaneously commences at the place of her arrival, (a coincidence which does and must necessarily often happen,) an immediate and universal panic is propagated, wherever the circumstances are known. Thus terror operating before the other cause or causes of pestilence come into

action, will throw communities into a state of general predisposition, if it be not sufficient to produce actual disease.

In places adjacent to countries subject to frequent visitations of pestilence, as Gibraltar and Spain in respect to the coast of Africa, the dread and anxiety of the public are necessarily almost incessant. The police establishments are perpetually on the alert. Travellers are detained and imprisoned. Persons having the misfortune to arrive in a state of disease from a place suffering under an epidemic, in any port at which the malady soon after commences, is immediately considered as the source from which it is propagated, as happened to an unfortunate man of the name of Santos, or Santo, coming from Cadiz or Malaga, and arriving at Gibraltar in August, 1804. In this case, instead of adopting efficient precautions, founded on a knowledge of the proper causes of the malady, to prevent its spreading, the means employed were only calculated to raise the public indignation against the innocent individual, who had the misfortune to have been amongst the first persons seized with the malady; and he was made to suffer, if not persecution, every sort of annoyance. In like manner boats or vessels suspected to have had communication with places supposed to be infected, are put in quarantine. Or, if the fact of their communication be established by proofs, they are burnt. This actually happened not many years ago upon a large scale at Gibraltar. In the Christian ports of the Mediterranean, ships or vessels known to have persons ill of the plague on board, are driven away without knowing where to find shelter. I have elsewhere stated an instance of this, which happened some years ago at Odessa. It is only a few months since a similar case occurred at Malta, as related in the London newspapers of the 15th of January last (1819). Howard, in his work upon Lazarettos, speaks of it as a common practice. He particularly mentions a Ragusian ship, which was driven away both from Ancona and Trieste.(Lazarettos, p. 11.)

The injurious effects of these proceedings are greatly aggravated, when the prohibition of intercourse, as in this case, is between countries, some of which are mainly dependent upon the others for their ordinary supplies of provisions. In such case many of the miseries of pestilence are suffered by anticipation, or without the disease appearing at all; and when it does occur, its otherwise inevitable calamities are multiplied in a dreadful ratio.

When, under the belief in contagion, epidemics pervade communities on a large scale, terror, distrust, and dismay, become universal. The country is afraid of the town, and the town of the country. Travellers dare not sleep at inns, and inns dare not receive travellers. Confidence between neighbours is at an end.

Even the ties of kindred are severed. The sick, deserted by friends and relations, are left to the care of mercenary attendants, generally of the most hardened description, who, if they do not accelerate their deaths, are too often impatient to profit by their spoils. But even these are sometimes disheartened, and sicken or fly. In Gibraltar in 1804 pestiferous patients were found dead in their beds without any person near them!

The dreadful effects of the belief in contagion are nowhere better exemplified than by the circumstances which attended the plague of Marseilles in 1720. By the 10th of September several parties of galley slaves, with which the magistrates had been supplied to remove bodies and to bury the dead, had successively perished. On that day a reinforcement is received of those galley slaves," and six, who are butchers by trade, are sent to serve in the slaughter-houses, where, all the butchers being dead or deserted, no one is left to kill oxen and sheep. By the 11th there are hardly any physicians or surgeons, who have not run away or perished. The people are in want of every thing. Provisions are not to be procured. No medicines or drugs are to be had, owing to the flight of the apothecaries, druggists, and grocers. The dying cannot make their wills for want of notaries; they cannot confess for want of priests. Women with child have no assistance in their labor. Misery is at its height. Those whom disease has missed perish by famine or despair. The fountains of charity are dried up. THE HEAVENS SEEM TO BE OF BRASS, AND THE EARTH OF IRON." (Res. 1. 323-4. Journal of the Plague of Marseilles.) It is not, I should apprehend, over-estimating the operation of terror, and all the other consequences of the belief in contagion, to impute to them nine-tenths of the whole calamity which happened on this occasion.

Such are the injurious effects of the dread, occasioned by the mere phenomena of pestilence, aggravated by the belief in contagion individually operating, and farther augmented by the influence of this belief, concentrated and set in motion by authority.

By the measures adopted under this belief for its prevention all the calamities of pestilence are necessarily aggravated. The effects of drawing lines of circumvallation, digging ditches, and placing cordons of troops round what are called infected cities, if the inhabitants were really laboring under a contagious disease, would be to multiply the chances of infection, as well as to increase mortality; for although a noxious atmosphere cannot generate contagion, compulsory residence among the infected would tend to spread the disease, whilst exposure to a deleterious air could not fail to render it more severe, and to increase its mortality; and the air itself being the principal cause of the disease, imprison