or in a large coal-scuttle containing wet ashes. This precaution is necessary to prevent setting fire to the floor, which would occur if the pot were placed directly on the floor or carpet, or by the sputtering of the sulphur, which may happen when it contains moisture. The vessel containing the sulphur should not be one with soldered joints, as the intense heat would melt the solder. The pot should be placed in the centre of the room; if the room is a large one, containing several thousand cubic feet of air-space, several pots should be provided, distributed at different points. Everything being in readiness, sufficient alcohol to moisten the sulphur should be poured on it, a lighted match applied, and when it is seen that the sulphur is well ignited the room should be left, and the door shut, and all cracks outside, including the keyhole, closed by paper, cotton, or other material. At the end of ten hours the fumigation is completed. Great care should be exercised in emptying the room of the sulphur-fumes, as these cannot be breathed, and are excessively irritating to the eyes and throat. If possible, a window should be opened from the outside, and through this the fumes permitted to escape; if this is impracticable, all the windows and doors of adjoining rooms should be opened, and then the door of the fumigated room, and through these outlets the fumes allowed to find an exit. Thorough airing will remove the slight odor which remains.

The fumigation being completed, all wood-work, as of floors, windows, and doors, and the walls and other surfaces, should be washed over with Standard Solution No. 3; particular attention being paid to cracks, crevices, and out-of-theway places, in which dirt ordinarily finds a lodgment, and from which it is with difficulty removed. A subsequent washing with hot water and soap will complete the cleansing process, and the room may be considered again habitable.

ADDITIONAL PREVENTIVE MEASURES, TO BE EMPLOYED IN THE ABSENCE AS WELL AS IN THE PRESENCE OF CONTAGION.

See that the whole house, from cellar to attic, is clean. Keep the cellar dry, well ventilated, and well whitewashed, and never allow, even for a day, garbage or other filth to be kept in it.

Open the windows of sleeping-rooms every day for as long a time as possible, and in every way obtain as much fresh air as possible.

Abolish the privy in the yard if there is a sewer in the street, and substitute a well-flushed water-closet; if there is no sewer, see that the vault is water-tight, emptied frequently, and kept inoffensive and innocuous by use of the Standard Solution No. 1, previously referred to, using a gallon of the solution for every gallon of material in the vault, and subsequently sprinkling the dry chloride of lime freely over the surface of the contents daily.

Be sure that there are no leaks or defective traps or joints in the drain-pipes of the house, through which the gases from the decomposing filth contained therein can enter to pollute the air you breathe.

When the children complain of sore throat, send promptly for a competent physician; a few hours' delay may cost their lives. If the disease is pronounced contagious, see that it is reported at once to the Department of Health, and keep the other children from schools of all kinds until a permit is procured for their return. Keep the patient and the attendants quarantined from other members of the family and house. The inspector of the district in which you live will call at your house as soon as the department is notified, and will give all possible advice and assistance, and will furnish the school-permits when the danger is passed.

School-permits will be given, on application to the inspector, as soon as the patient has fully recovered and the sick-room has been disinfected; in cases of scarlatina and measles this will not be until desquamation-or peeling off of the skin--is completed. The measures here recommended are to be used. in all contagious diseases, whether diphtheria, scarlet fever, measles, small-pox, or others.

VENTILATION WITH AIR FROM

SUPERIOR

COUCHES IN PLACE OF INFERIOR COUCHES.

By EDWIN CHADWICK, C.B.

IN sanitary inquiries my attention was early directed to instances of couches of air of malarious influence, such as this: A medical officer, pointing to a mist spread like a sheet over a valley, said, "That sheet just covers the bulk of my patients; out of it, or above it, I have nothing scarcely but midwifery cases and accidents. I have had instances of children. whose heads were above a visible mist escaping attacks, while the smaller children covered by the mist suffered from them; of examples of the occupiers of the cellars, and the lower stages in towns, suffering from cholera and other epidemic visitations, while those living in the upper flats or highest stories entirely escaped from them, except in the attics, for which there was special reason; cases of experiences in India, where men could not travel in safety at night across valleys, while men on elephants, being above the malarious couch, could do so; of people raising their habitations on stilts to escape the mephitic influences of which they have had experience."

Mr. Glaisher, the aeronaut, writes to me: "When in the car of a balloon, I have been struck with the definite boundary of mists at times when there has been but little generally, and I found afterward that the mists were located over marshes, or clayey soil, when gravelly soil was free. The ventilation of the Underground Railway could be effectually carried out by your suggestion."

The general effect of land drainage has been to reduce mists, and in some instances to remove them entirely. In such instances it has reduced or removed the plague of midges in England. In one instance in Algeria of which I was informed, the drainage of a district, and its close cultivation, entirely removed the plague of mosquitoes which had rendered it almost

uninhabitable. In the Fen districts of Lincolnshire, the land drainage has reduced mists, and so reduced ague that ounces of bark are not now used where pounds were used formerly. It is for entomologists to show on what these animalcules subsist where there are no human or animal subjects to prey upon, and what is the superficial extent of their feeding ground. On the occasion of choleraic visitations, extraordinary developments of insect life were in some instances observed, generally in low-lying couches, but they passed without any examination of which I am aware. Swallows and insectivorous-feeding birds appear habitually to fly now in pursuit of prey. I point out these incidents for the observation of naturalists, and the favor of information from them.

From Highgate Hill I have observed mists spread over the Metropolis like a blanket, and the upper dome of St. Paul's Cathedral appearing clear and bright above it like a spike through the blanket.

I have ascended that dome and found there a clear, freshening breeze, as good in sensation as any on the Surrey hills; while the air beneath in the adjacent streets was comparatively stagnant and unrefreshing.

On a discussion of the subject with the late Dr. Neil Arnott, a pre-eminently good sanitarian and an able mechanician, it appeared that we might form a pure-air company, which would engage to draw the air from a suitable height above to common couches, and distribute it into houses by engine power, or as gas is distributed, and do it with a profit at a very low rate, or for some few shillings a year give even a better air than people generally obtain in suburban residences. The principle may now be presented for consideration, for hospital construction, and the excessive mortality that is prevalent in the larger hospitals beyond that which prevails in the smaller ones, and in reduction of the necessity of washing the air in the town hospitals for the performance of operations.

I have visited hospitals in Paris where the methods of internal ventilation are, in my view, excellent and superior, but where all draw in the air from the lower couches of the outside street air. I do not know of one instance where the expedient of drawing in a superior air from a height has been adopted or thought of. In England I have known of hospitals very well

ventilated---internally, mechanically-which have drawn their external air from lower couches that were positively very bad, and the more the wards were ventilated the worse they often were. Indeed, it is sometimes proposed as a principle, as against that of extraction, that ventilation is best effected by "currents of fresh air brought in by open windows placed in opposite sides of the wards." But this "fresh air" is the common street air, really foul air polluted by street emanations from sewers and cesspools, requiring washings before operations can be safely performed. It is well known that surgical operations cannot be performed with safety in town air (unless it is washed) that may be performed with increased chances of favorable results in a good suburban air.

In Paris two systems of ventilation were in competition when I visited the hospitals: one of "propulsion," or driving in the air; the other of "aspiration," or of drawing it out by suction. It appeared that the practice of propulsion drove the air in heaps, leaving corners stagnant; whilst the method of aspiration, or of suction, operated perfectly in removing the air the nearest from the points of vitiation in the time and mode required, and to introduce really fresh air from the points farthest from vitiation and at the temperature required; and also to maintain passages and cabinets at a temperature equal to that of the interior rooms. Notwithstanding the default of ventilating with the generally cesspool-tainted and impure street air, the effect of the system of "aspiration" appeared to be in advance of at least one-fourth of the common methods of hospital ventilation.

This principle of aspiration appears to me to be peculiarly adapted to drawing in the air from the superior couch, obtained from two, three, four, or five hundred feet, or whatever height it may be obtained.

The principle is peculiarly applicable to India and to Eastern cities generally, for the securing of refreshing sleep free from the plague of mosquitoes.

A friend, a great traveller, found out that mosquitoes lived and fed exclusively in the animalized gases diffused among the lower couches of air. He suffered intensely from the bite of these insects, and, to escape them when he came near the coast, he made his bed aloft on the crosstrees of the mainmast;