[DR ARNOTT ON VENTILATION AS A PREVENTIVE OF DISEASE.]
Dr Neil Arnott has addressed a letter on this subject to the 'Times' newspaper. Any expression of opinion by him on such a subject, and more particularly with reference to the prevailing epidemics, must be deemed of so much importance, that we are anxious, as far as in our power, to keep it before the world. He commences by assuming, what will readily be granted, that fresh air for breathing is one of the essentials to life, and that the respiration of air poisoned by impure matter is highly detrimental to health, insomuch that it will sometimes produce the immediate destruction of life. The air acquires impurities from two sources in chief—solid and liquid filth, and the human breath. Persons exposed to these agencies in open places, as the manufacturers of manure in Paris, will suffer little. It is chiefly when the poison is caught and retained under cover, as in close rooms, that it becomes notedly active, its power, however, being always chiefly shown upon those whose tone of health has been reduced by intemperance, by improper food or drink, by great fatigue and anxiety, and, above all, by a habitual want of fresh air.
Dr Arnott regards ventilation not only as a ready means of rendering harmless the breath of the inmates of houses, as well as those living in hospitals and other crowded places, but as a good interim-substitute for a more perfect kind of draining than that which exists. 'To illustrate,' he says, 'the efficacy of ventilation, or dilution with fresh air, in rendering quite harmless any aërial poison, I may adduce the explanation given in a report of mine on fevers, furnished at the request of the Poor-Law Commissioners in 1840, of the fact, that the malaria or infection of marsh fevers, such as occur in the Pontine marshes near Rome, and of all the deadly tropical fevers, affects persons almost only in the night. Yet the malaria or poison from decomposing organic matters which causes these fevers is formed during the day, under the influence of the hot sun, still more abundantly than during the colder night; but in the day the direct beams of the sun warm the surface of the earth so intensely, that any air touching that surface is similarly heated, and rises away like a fire balloon, carrying up with it of course, and much diluting, all poisonous malaria formed there. During the night, on the contrary, the surface of the earth, no longer receiving the sun's rays, soon radiates away its heat, so that a thermometer lying on the ground is found to be several degrees colder than one hanging in the air a few feet above. The poison formed near the ground, therefore, at night, instead of being heated and lifted, and quickly dissipated, as during the day, is rendered cold, and comparatively dense, and lies on the earth a concentrated mass, which it may be death to inspire. Hence the value in such situations of sleeping apartments near the top of a house, or of apartments below, which shut out the night air, and are large enough to contain a sufficient supply of the purer day air for the persons using them at night, and of mechanical means of taking down pure air from above the house to be a supply during the night. At a certain height above the surface of the earth, the atmosphere being nearly of equal purity all the earth over, a man rising in a balloon, or obtaining air for his house from a certain elevation, might be considered to have changed his country, any peculiarity of the atmosphere below, owing to the great dilution effected before it reached the height, becoming absolutely insensible.
'Now, in regard to the dilution of aërial poisons in houses by ventilation, I have to explain that every chimney in a house is what is called a sucking or drawing air-pump, of a certain force, and can easily be rendered a valuable ventilating-pump. A chimney is a pump—first, by reason of the suction or approach to a vacuum made at the open top of any tube across which the wind blows directly; and, secondly, because the flue is usually occupied, even when there is no fire, by air somewhat warmer than the external air, and has therefore, even in a calm day, what is called a chimney-draught proportioned to the difference. In England, therefore, of old, when the chimney breast was always made higher than the heads of persons sitting or sleeping in rooms, a room with an open chimney was tolerably well ventilated in the lower part, where the inmates breathed. The modern fashion, however, of very low grates and low chimney openings, has changed the case completely; for such openings can draw air only from the bottom of the rooms, where generally the coolest, the last entered, and therefore the purest air, is found; while the hotter air of the breath, of lights, of warm food, and often of subterranean drains, &c., rises and stagnates near the ceilings, and gradually corrupts there. Such heated, impure air, no more tends downwards again to escape or dive under the chimneypiece, than oil in an inverted bottle, immersed in water, will dive down through the water to escape by the bottle's mouth; and such a bottle, or other vessel containing oil, and so placed in water with its open mouth downwards, even if left in a running stream, would retain the oil for any length of time. If, however, an opening be made into a chimney flue through the wall near the ceiling of the room, then will all the hot impure air of the room as certainly pass away by that opening as oil from the inverted bottle would instantly all escape upwards through a small opening made near the elevated bottom of the bottle. A top window-sash, lowered a little, instead of serving, as many people believe it does, like such an opening into the chimney flue, becomes generally, in obedience to the chimney draught, merely an inlet of cold air, which first falls as a cascade to the floor, and then glides towards the chimney, and gradually passes away by this, leaving the hotter impure air of the room nearly untouched.
'For years past I have recommended the adoption of such ventilating chimney openings as above described, and I devised a balanced metallic valve, to prevent, during the use of fires, the escape of smoke to the room. The advantages of these openings and valves were soon so manifest, that the referees appointed under the Building Act added a clause to their bill, allowing the introduction of the valves, and directing how they were to be placed, and they are now in very extensive use. A good illustration of the subject was afforded in St James's parish, where some quarters are densely inhabited by the families of Irish labourers. These localities formerly sent an enormous number of sick to the neighbouring dispensary. Mr Toynbee, the able medical chief of that dispensary, came to consult me respecting the ventilation of such places, and on my recommendation had openings made into the chimney flues of the rooms near the ceilings, by removing a single brick, and placing there a piece of wire gauze with a light curtain flap hanging against the inside, to prevent the issue of smoke in gusty weather. The decided effect produced at once on the feelings of the inmates was so remarkable, that there was an extensive demand for the new appliance, and, as a consequence of its adoption, Mr Toynbee had soon to report, in evidence given before the Health of Towns Commission, and in other published documents, both an extraordinary reduction of the number of sick applying for relief, and of the severity of diseases occurring. Wide experience elsewhere has since obtained similar results. Most of the hospitals and poor-houses in the kingdom now have these chimney-valves; and most of the medical men, and others who have published of late on sanitary matters, have strongly commended them. Had the present Board of Health possessed the power, and deemed the means expedient, the chimney openings might, as a prevention of cholera, almost in one day, and at the expense of about a shilling for a poor man's room, have been established over the whole kingdom.
'Mr Simpson, the registrar of deaths for St Giles's parish, an experienced practitioner, whose judgment I value much, related to me lately that he had been called to visit a house in one of the crowded courts, to register the death of an inmate from cholera. He found five other persons living in the room, which was most close and offensive. He advised the immediate removal of all to other lodgings. A second died before the removal took place, and soon after, in the poor-house and elsewhere, three others died who had breathed the foul air of that room. Mr Simpson expressed to me his belief that if there had been the opening described above into the chimney near the ceiling, this horrid history would not have been to tell. I believe so too, and I believe that there have been in London lately very many similar cases.
'The chimney-valves are part of a set of means devised by me for ventilation under all circumstances. My report on the ventilation of ships, sent at the request of the Board of Health, has been published in the Board's late Report on Quarantine, with testimony furnished to the Admiralty as to its utility in a convict ship with 500 prisoners. My observations on the ventilation of hospitals are also in the hands of the Board, but not yet published. All the new means have been freely offered to the public, but persons desiring to use them should be careful to employ competent makers.'
Having seen Dr Arnott's ventilators in operation in London and elsewhere, we can venture to recommend them as a simple and very inexpensive machinery for ventilating rooms with fires. The process is indeed generally known, and would be more extensively applied if people knew where to procure the ventilators. We have had many letters of inquiry on this subject, and could only refer parties to 'any respectable ironmongers.' But unfortunately, as it appears, there are hundreds of respectable ironmongers who never heard of the article in question, and our recommendation goes pretty much for nothing. Curious how a little practical difficulty will mar a great project! We trust that the worthy doctor will try to let it be known where his ventilators are to be had in town and country.