A traveling revivalist displays charts of the Eastern continents to illustrate the vast area of territories still in need of missionary labors. The extent of the field for sanitary reform might be realized by any observer strolling the streets of a large city in the twilight of a summer morning. In the tropics—even on the cool tablelands of Northern Mexico, he would see thousands of sleepers encamped upon the texadas, or flat roofs of their dwelling-houses; but in the United States, in Great Britain, France, Germany and Austria he would see 999 of a 1000 windows tightly closed, even in a temperature making indoor confinement positive torture.

Night air? What are you afraid of?" asked Miss Florence Nightingale in her reports from the Crimean hospitals; "do you suppose God's free air is made deadly by the temporary absence of light? You surely cannot expect to breathe day-air after sunset; your only choice is between the life-giving, health-restoring night-air of the outdoor world and the vitiated, sickening night-air of your sweltering dormitories."

But what the self-torturers are really afraid of is a "draught;" in other words, air in motion. Perceptible currents of air, no matter how pure, no matter how passionately welcomed by the miasma-clogged lungs, they dread as messengers of death. Their fear of night-air is founded chiefly on the circumstance that the cooling of the atmosphere generates air-currents within a few hours after the sunset even of the sultriest day. So they close their bedroom windows or nail them down; they invent double window-sashes and "weather-strips," to exclude the slightest breath of life-air.

And yet the sanitary value of fresh air is generally proportioned to the persistency of its currents. Air in motion removes the impurities of the atmosphere. It renews the supply of oxygen. Its ministrations attend both to the disinfection and the nourishment of the respiratory organs. The sanitary difference between fresh air in motion and stagnant indoor air is that between the pure water of a running fountain and the festering slime of a cesspool.

The comparatively low temperature of night-air only increases its value for expurgative purposes. The appalling, drug-defying mortality of a large city sweltering under the glare of the dog-day sun, is abated by the first spell of cooler weather. The veering of a midsummer breeze from south to northwest reduces the death-rate of infants two-thirds. Canadian trappers who leave their supply-camp with a bad cough, get rid of it on the fifth or sixth day "out." They may get footsore, and if game is scarce, hipped and homesick, but the feeling of haleness about the chest continues. Night-frosts do not affect it. Fatigues rather improve it. They may wake up with a feeling of frost-cramp from their chillblained toes to their shivering knees, but the lungs are at ease; no cough, no asthmatic distress, no stitch-like pains, no night-fever.

An old campaigner would laugh at the idea of "colds" being taken in the open air. He knows that they germinate in close bedrooms and flourish in musty beer-shops, but vanish in the prairie-wind.

Houses cannot be kept too airy, no room or chamber should ever be kept permanently closed for days together. Never mind about the improvement of ventilatory contrivances: patent

ventilators" are mostly calculated to humor the prejudice against perceptible air-currents. They are intended to smuggle in a modicum of fresh air unnoticed, near the edge of the ceiling, in a roundabout way through halls and antechambers. One open window is worth a dozen of such compromise tricks.

Open the dining-room windows in the forenoon; and the kitchen windows in the afternoon; no revolving-fan can compete with the effect of a direct influx of atmospheric air. If you teach a class or work in a warehouse or counting-house, prevail upon the managers to ventilate the place during the dinner-recess; or else try to do your work in the airiest corner, near a window or near the door of an airy hall. In ill-ventilated rooms the azote miasma has its centers of destiny that can be avoided with a little management.

But at all events get rid of the night-air superstition, and enjoy the blessings of an airy bedroom—the luxury, I may add. A natural instinct may be suppressed, but needs but little encouragement to resume its normal functions, like a river returning to its ancient channel. Thus, the fresh-air instinct. In families cursed with the night-air delusion children are often fuddled with miasma till they prefer it to fresh air and dislike to sleep near an open window. But in a single month that aversion can be changed into a decided predilection, till the cool breath of the night-wind becomes a chief condition of a good night's rest, and the closing of the bedroom windows creates a feeling of uneasiness, not unlike the discomfort induced by an attempt to sleep with your head under the blankets. In the sleeping dens of the French village taverns, where after September the window-sashes are actually nailed down, the children of a hygienic home would pine for a draught of oxygen as a sweltering traveler thirsts after fresh water.

Besides open windows, Dio Lewis recommends an open fireplace and a good wood fire all night; but that is a matter of taste; an extra blanket will serve the same purpose, and the danger of damp bed-clothes in mid-winter has been as strangely overrated as the perils of cold drinking-water in midsummer.

In stormy nights a half-closed "rain-shutter" (a window-blind with broad bars) will keep the room perfectly dry without excluding the air. If the mercury sinks below zero, close every window in the house. Intense cold is a disinfectant that purifies even the air of the hide-covered dungeons where the natives of the Polar regions pass the long winter nights.

In the dog-days, on the other hand, do not be satisfied with anything less than a through-draft; open every window in and around the bedroom.

It should also be remembered that the lung-poison of a stifling bed-chamber may undo the sanitary benefit of a long day passed in out-door exercise. European tourists can combine the useful with the agreeable by doing their sightseeing afoot, but should not forget that Alpine morning-breezes may fail to neutralize the bedroom air of a South-German tavern.

Nor can the purest atmosphere of our planet—that of the breezy ocean—be relied upon to counteract the monstrous air-filth of an unventilated cock-pit. Sailors, in spite of an abundance of outdoor exercise, thus often contract lung-disorders, and Captain Cook relates that the natives of the South Sea Islands, after visiting the sailors' cabin of his ship, were seized with strange respiratory afflictions: sneezing-fits, coughs, and pains in the chest, together with a kind of pulmonary fever. Generations of outdoor life had failed to protect these children of Nature against the effects of a brief exposure to a concentrated lung-poison; nay, its effect upon their unprepared organism was more violent than that experienced by persons in whom habit had established a sort of "physiological tolerance"—akin to the strange adaption that enables habitues to swallow enormous doses of arsenic and opium.

For Professor Bates, in his "Naturalist on the River Amazon," states that the natives of Western Brazil have learned by sad experience to avoid a visit to the interior of a white man's dwelling, as travelers in Java would shun the valley of the Upas Tree. Catarrh germs, in their organism, take the form of consumption-microbes, and there appears to be no cure for that disease in the sweltering river swamps of the tropics. The stricken native coughs night and day, and the disease in that virulent modification of its development, terminates life in less than two years. The Quahiba Indians, adds the same traveler, would sooner load the horse of a Caucasian visitor with presents than carry their hospitality to the fatal degree of allowing him to pass a night in their cabins. "Do you bring influenza, Señor?" they ask with a look of alarm, when a stranger approaches their wigwams.