tenance of the vigorous actions of all the parts, and especially of the brain, and spinal column, the great fountains of nervous power. If this process is long continued, even though the air be but slightly deteriorated, the effects will be evident in the languid and feeble action of the muscles, the sunken eye, the squalid hue of the skin, the unnatural irritability of the nervous system, a disinclination to all mental and bodily exertion, and a tendency to stupor, headache and fainting. If the air is very impure, i. e. has but little or no oxygen and much carbonic acid, then the imperfect and poisoned blood will act with a peculiar and malignant energy on the whole system, and especially on the brain, and convulsions, apoplexy, and death must ensue.

Abundant instances of the beneficent effects of pure air, and the injurious and fatal results of breathing that which is impure, might be cited from the history of hospitals and prisons, and writers generally on health and education. In the Dublin Hospital, between the years 1781 and 1785, out of 7650 children, 2944 died within a fortnight of their birth—that is, more than one in three. Dr. Clark, the physician, suspecting the cause to be an imperfect supply of pure air, caused it to be introduced by means of pipes into all of the apartments, and in consequence, during the three following years, only 165 out of 4242 died within the two first weeks of their birth-that is less than one in twenty. Dr. Buchan, at a little earlier date, by the same arrangement reduced the mortality of children in a hospital in Yorkshire, from fifty in one hundred to one in fifty. In these two cases there was an immense saving of human life. But the good done by these intelligent and observing physicians was not confined to these hospitals. For in a few years, the results of their observation and labors led to the introduction of more perfect arrangements for a supply of pure air in all structures of a similar character in England and elsewhere. And at this hour there are hospitals in this country and in England, in which there is a larger number of cubic feet of air, and that kept pure by perfect means of ventilation, allowed to each patient, than is contained in many school-rooms occupied by 20, 30, or 40 children, heated with a close stove, and provided with no means of ventilation except such as time and decay have made.

The diminished mortality of prisons, and the almost entire disappearance of that terible scourge, the jail fever, so frequent before the days of Howard, is to be attributed mainly to the larger allowance and regular supply of pure air secured by improved principles of prison architecture and discipline. There are instances on record, where the inmates of prisons have escaped the visitation of some prevalent sickness, solely on the ground of their cells being better provided with pure air, than the dwelling-houses all around them. The prisoners in the Tolbooth, in Edinburgh, were unaffected by the plague, which caused such dreadful mortality in that city, in 1645, and this exemption was attributed to their better supply of pure air. Humboldt in his Personal Narrative, mentions the case of a seaman who was at the point of death, and was obliged to be removed from his hammock, which brought his face to within a foot of the deck, into the open air, in order to have the sacrament administered as is the custom on board

of Spanish vessels. In this place he was expected to die, but the change from the stagnant, impure atmosphere in which his hammock was hung, to the fresh, purer atmosphere of the deck, enabled the powers of life to rally, and from that moment he began to recover. Even the miserable remnant of the party who were confined in the Black Hole of Calcutta, sick as they were of a malignant, putrid fever, recovered on being admitted to the fresh air of heaven, under proper medical treatment. But the history of this whole affair is a terrible lesson on this subject, which though often repeated, cannot be too often dwelt upon. This Black Hole is a prison in Calcutta, 18 feet square, into which the Nabob of Bengal after the capture of Fort William from the British in 1756, thrust 146 English prisoners. The only opening to the air, except the door, was by two windows on the same side, strongly barred with iron. Immediately on the closing of the door a profuse perspiration burst out on every prisoner. In less than an hour their thirst became intolerable, and their breathing difficult. The cry was universal and incessant for air and water, but the former could only come in through the grated windows, and the latter, when supplied by the guards without, only aggravated their distress. All struggled to get near the windows, and in this death-struggle as it were, many were trampled under foot. In less than three hours several had died, and nearly all the rest were delirious and prayed for death in any form. On the opening of the doors at six o'clock in the morning, less than eleven hours after it was closed, death had indeed come to the relief of 123 out of the 146, and the remainder had sunk down on their dead bodies sick with a putrid fever. Now what did all this anguish, and these murderous results spring from? From breathing over and over again air which had become vitiated and poisonous by passing repeatedly through the lungs, and by exhalations from the surface of the bodies of the persons confined there. "This terrible example," says Dr. Combe in his Principles of Physiology, "ought not to be lost upon us, and if results so appalling arise from the extreme corruption of the air, results, less obvious and sudden, but no less certain, may be expected from every lesser degree of impurity."

"In our school-rooms," says Dr. Bell, "churches, hospitals and places of public evening amusements, and even in our private dormitories, we not unfrequently make near approaches to the summary poisoning process of the Black Hole at Calcutta." We do not appreciate the magnitude of the evils produced by breathing frequently, even for a short period at any one time, a vitiated atmosphere, because the ultimate results are both remote, and the accumulation of repeated exposures. Besides, the immediate effects may be not only slight, but may apparently disappear on our breathing again a free and pure air, so that we forget to appreciate the temporary inconvenience or suffering, and to refer them to their true cause. How often do we retire at night, perfectly well, and rise up in the morning unrefreshed with sleep, with an aching head, a feverish skin, and a sick stomach, without reflecting that these symptoms of a diseased system are the necessary effects of breathing the atmosphere of a chamber, narrow

in its dimensions, closed against any fresh supply from without, and not unlikely, made still more close by a curtained bed, and exhausted of even its small quantity of oxygen, by a burning fire or lamp? These same causes, a little longer in operation, or a little more active, would produce death as surely, although not as suddenly, as a pan of ignited charcoal in the room. Who has not noticed that the fainting and sickness which so often visit persons, and especially females of delicate health in crowded churches and lecture-rooms, only occurs after the air has become overheated and vitiated, by having been a long time breathed, and that an exposure to the open air generally restores the irregular or suspended circulation of the blood? In the relief and newness of life which we experience on emerging from such places of crowded resort, we forget that the weariness and languor, both of mind and body which we suffered within, were mainly the depressing effects of the imperfectly vitalized blood, and that the relief is simply the renovated life and vigor, which the same blood, purified of its carbon by coming in contact with the oxygen of the air, imparts to the whole system, and especially to the brain. But in spite of our forgetfulness of the cause, or the apparent disappearance of the temporary inconvenience and distress, which should warn us to beware of a repetition of the same offence against the laws of comfort and health, repeated exposures are sure to induce or develope any tendency to disease, especially of a pulmonary or nervous character, in our constitutions, and to undermine slowly the firmest health. Who can look round on a workshop of fifteen or twenty females, breathing the same unrenewed atmosphere, and sitting perhaps in a position which constrains the free play of the lungs, and not feel that disease, and in all probability, disease in the form of that fell destroyer of our fair country women, consumption, will select from among those industrious girls, its ill starred victims? The languor, debility, loss of appetite, difficulty of breathing, coughs, distortion of the frame, (fallen away from the roundness natural to youth and health,) nervous irritability, and chronic affections of various kinds, so common among females in factories, even in our own healthy New England, or those who have retired from such factories to their own homes to die, or wear out a dying life all their days, are the natural fruits of an exposure, day after day, to an atmosphere constantly becoming more impure from the vitiated breath of forty or fifty persons, and rendered still more unfit for respiration by dust and minute particles floating in it, tending to irritate the already inflamed and sensitive membrane which incloses the air cells of the lungs. To this exposure in the workroom should be added the want of cheerful exercise, and innocent recreation in the open air, and the custom of herding together at night in the small, unventilated sleeping apartments of our factory boarding-houses.

In the school-room the same poisoning process goes on day after day, and if the work is less summary, it is in the end more extensively fatal, than in the Black Hole of Calcutta. Every man and woman, who received any portion of their early education in the common school, can testify to the narrow dimensions, and low ceiling of the school

rooms, and to the discomfort arising from the close, stagnant, offensive atmosphere, which they were obliged to breathe. Who does not remember the comparative freshness and vigor of mind and body with which the morning's study and recitations were begun, and the languor and weariness of body, the confusion of mind, the dry skin, the flushed cheek, the aching head, the sickening sensations, the unnatural demand for drink, the thousand excuses to get out of doors, which came along in succession as the day advanced, and especially in a winter's afternoon, when the overheated and unrenewed atmosphere had become obvious to every sense? These were nature's signals of distress, and who can forget the delicious sensations with which her holy breath, when admitted on the occasional opening of the door, would visit the brow and face, and be felt all along the revitalized blood, or the newness of life with which nerve, muscle, and mind were endued by free exercise in the open air at the recess, and the close of the school? Let any one who is sceptical on this point visit the school of his own district, where his own children perhaps are condemned to a shorter allowance of pure air than the criminals of the State, and he cannot fail to see in the pale and wearied countenances of the pupils, the languor and uneasiness manifested, especially by the younger children, and exhaustion and irritability of the teacher, a demonstration that the atmosphere of the room is no longer such as the comfort, health and cheerful labor of both teacher and pupils require.

In this way the seeds of disease are sown broadcast among the young, and especially among teachers of delicate health. "In looking back," says the venerable Dr. Woodbridge in a communication on school-houses to the American Institute of Instruction, "upon the languor of fifty years of labor as a teacher, reiterated with many a weary day, I attribute a great proportion of it to mephetic air; nor can I doubt, that it has compelled many worthy and promising teachers to quit the employment. Neither can I doubt, that it has been the great cause of their subsequently sickly habits and untimely decease." A physician in Massachusetts, selected two schools, of nearly the same number of children, belonging to families of the same condition of life, and no causes, independent of the circumstances of their several school-houses, were known to affect their health. One house was dry and properly ventilated-the other damp, and not ventilated. In the former, during a period of forty-five days, five scholars were absent from sickness to the amount in the whole of twenty days. In the latter, during the same period of time and from the same cause, nineteen children were absent to an amount in all of one hundred and forty-five days, and the appearance of the children not thus detained by sickness indicated a marked difference in their condition as to health.

The necessity of renewing the atmosphere, does not arise solely from the consumption of the oxygen, and the constant generation of carbonic acid, but from the presence of other destructive agents, and ́ impurities. There is carburetted hydrogen, which Dr. Dunglinson in his Physiology, characterizes, "as very depressing to the vital unctions. Even when largely diluted with atmospheric air, it occa

sions vertigo. sickness, diminution of the force and velocity of the pulse, reduction of muscular vigor and every symptom of diminished power." There is also sulphuretted hydrogen, which the same author says, in its pure state, kills instantly, and in its diluted state, produces powerful sedative effects on the pulse, muscles, and whole nervous system. There are also offensive and destructive impurities arising from the decomposition of animal and vegetable matter in contact with the stove, or dissolved in the evaporating dish.

The objects to be attained are-the removal of such impurities, as have been referred to, and which are constantly generated, wherever there is animal life and burning fires, and the due supply of that vital principle, which is constantly consumed by breathing and combustion. The first can be in no other way effectually secured, but by making provision for its escape into the open air, both at the top and the bottom of the room; and the second, but by introducing a current of pure air from the outside of the building, warmed in winter by a furnace, or in some other mode, before entering the room. The two processes should go on together-i. e. the escape of the vitiated air from within, and the introduction of the pure air from without. The common fireplace and chimney secures the first object very effectually, for there is always a strong current of air near the floor, towards the fire, to support combustion, and supply the partial vacuum in the chimney occasioned by the ascending column of smoke and rarified air, and in this current the carbonic acid and other impurities will be drawn into the fire and up the chimney. But there is such an enormous waste of heat in these fireplaces, and such a constant influx of cold air through every crevice in the imperfect fittings of the doors and windows, to supply the current always ascending the chimney, that this mode of ventilation should not be relied on. The common mode of ventilating, by opening a window or door, although better than none, is also imperfect and objectionable; as the cold air falls directly on the head, neck, and other exposed parts of the body, when every pore is open, and thus causes discomfort, catarrh, and other more serious evils, to those sitting near, besides reducing the temperature of the whole room too suddenly and too low. This mode, however, should be resorted to at recess.

There should be one or more openings, expressly for ventilation, both at the top and the bottom of the room, of not less than twelve inches square, capable of being wholly or partially closed by a slide of wood or metal, and, if possible, these openings, or the receptacle into which they discharge, should be connected with the chimney or smoke-flue, in which there is already a column of heated air. By an opening in or near the ceiling, the warmer impurities (and air when heated, and especially when over-heated, will retain noxious gases longer) will pass off. By an opening near the floor, into the smokeflue, the colder impurities (and carbonic acid, and the other noxious gases, which at first rise, soon diffuse themselves through the atmosphere, cool, and subside towards the floor) will be drawn in to supply the current of heated air and smoke ascending the chimney.