overexertion, and yet the rest condition is essential for building up the diseased lung. The third method of treatment involves fresh air, in order to improve the oxygenating character of the blood. If one remembers that the oxygen in the blood is the chief scavenger of the body and that the vitality of the red corpuscles and their abundance is an essential factor in curing the disease, it will be seen why fresh air is so important. The tendency to-day is to insist on fresh air and to lay less stress on the climate than was formerly done. It was not uncommon a few years ago for a physician, recognizing consumption, to send his patient away, partly because he honestly believed the climate of Arizona or Colorado or the Sandwich Islands was better than that where the patient lived, and partly, without doubt, because he was glad to get rid of a disease which he knew it was not in his power to cure. To-day, unless the patient can go to a properly equipped and maintained sanitarium, physicians recognize that conditions may be as beneficial at home as elsewhere and, provided the three factors mentioned--good food, rest, and fresh air--can be obtained, the chances for recovery are better because of better care at home than elsewhere. But fresh air is essential, and this means that the patient must spend twenty-four hours a day in the open. He must eat and sleep out of doors. He must not go into the house when it rains, nor when it snows, and even with the thermometer at zero he must still stay out, wrapping himself up, to be sure, so that his body is not cold, but breathing into his lungs the life-giving, vitalizing, oxygen-bearing air. The side porch of a house may be very easily transformed into a room with a cot bed and an easy chair, where the consumptive may stay continually, and while it is convenient to have a window or a door opening from the porch into a room where the patient may be dressed and bathed, this is not essential, although customary in sanitariums. If no side porch exists, it is possible to build such a porch, and the picture shows how such a construction may be added to even a small house in the city (Fig. 75). If this is out of the question, the windows of a room may be left open all the time, or the patient may lie on a bed, the head of which either extends through the window or is arranged to admit fresh air by a specially devised window tent. Educational campaigns have been vigorously prosecuted for the past ten years, and gradually through the world is spreading a growing appreciation of the dangers of this disease. The effect of this increasing knowledge is reflected by a continually decreasing number of deaths in proportion to the population. The following diagram (Fig. 76) shows how this law is obeyed in New York State, the downward tendency of the line since 1890 being very plainly marked. [Illustration: FIG. 75.--Outdoor sleeping porch for tuberculosis patients.]