[Sidenote: Occupations] Above all, outdoor occupations should, when possible, be chosen in preference to indoor occupations, such as working on a farm rather than in a factory. It would help solve some of the greatest problems of civilization, if, in consequence of an increased liking for outdoor life, larger numbers of our population should join the "back-to-the-farm" movement. Leaving the country for the city is often disastrous even for the purpose in view, namely to gain wealth. For wealth gained at the expense of health always proves in the end a bitter joke. The victim proceeds through the rest of his life to spend wealth in pursuit of health. Section IV--Outdoor Sleeping Unfortunately most people can not live out of doors all of the time, and many are so situated that they can not even secure ventilation, granted that they want it. But there is one important part of the twenty-four hours when most people can completely control their own air supply. This is at night. We spend a third of our time in bed. Most of us live such confined lives during the day that we should all the more avail ourselves of our opportunities to practise air hygiene at night. [Sidenote: Tuberculosis] [Sidenote: Well Persons] It is the universal testimony of those who have slept out-of-doors that the best ventilated sleeping-room is far inferior in healthfulness to an outdoor sleeping-porch, open tent, or window tent (large enough to include the whole bed). For generations, outdoor sleeping has occasionally been used as a health measure in certain favorable climates and seasons. But only in the last two decades has it been used in ordinary climates and all the year round. Dr. Millet, a Brockton physician, began some years ago to prescribe outdoor sleeping for some shoe-factory workmen who were suffering from tuberculosis. As a consequence, in spite of their insanitary working-places (where they still continued to work while being treated for tuberculosis), they often conquered the disease in a few months. It was largely this experience which led to the general adoption, irrespective of climate, of outdoor sleeping for the treatment of tuberculosis. The practise has since been introduced for nervous troubles and for other diseases, including pneumonia. Latterly the value of outdoor sleeping for _well_ persons of all classes, infants and children as well as adults, has come to be widely recognized. [Sidenote: Vital Resistance] Outdoor sleeping increases the power to resist disease, and greatly promotes physical vigor, endurance, and working power. [Sidenote: Night Air]