1892. This essay consists of articles which originally appeared in "The Christian Advocate" and some additional matter of importance. The principles underlying it are that pure air is life and the want of it death; that deep breathing is essential to vigorous health; and that chronic disease, except when the result of accident, is caused by neglecting, and by transgressing, little by little for a long time, and can only be cured by attending and obeying the laws of health for a long time.