If we live a natural open-air life we shall have but little need of doctors or medicine. Many of our grandmothers' notions on how to keep well have changed in recent years. Old-fashioned remedies made from roots and herbs have been almost completely replaced by better habits of life and common-sense ideas. We used to believe that night air was largely responsible for fevers and colds. Doctors now say that one of the surest ways to keep well is to live and sleep in the open air. In many modern houses the whole family is provided with outside sleeping porches with absolutely no protection from the outside air but the roof. I have followed the practice of sleeping in the open air for some time and in midwinter without discomfort have had the temperature of my sleeping porch fall to six degrees below zero. Of course it is foolish for any one to sleep exposed to rain or snow or to think that there is any benefit to be derived from being cold or uncomfortable. The whole idea of open-air sleeping is to breathe pure fresh air in place of the atmosphere of a house which under the best conditions is full of dust and germs. If we become outdoor sleepers coughs and colds will be almost unknown. General Sherman once wrote a letter in which he said that he did not have a case of cold in his entire army and he attributed it to the fact that his soldiers slept and lived in the open air.