Lest it be inferred that I design to intimate that any one could at once imitate my cold air experiments with impunity, immediately upon changing his method of living, I hasten to say that not all could do this, any more than they could imitate the muscular feats of an athlete. As the depraved muscular system has to be built up by degrees and by long practice, so the life-long sweltered skin can become accustomed to extreme changes of temperature only by a somewhat gradual change of habit. Besides, it takes some time for the general system to come under the influence of a pure diet; and, again, the best of remedies have to be graduated in amount to the present condition of the patient. However, I am sure that most persons who will accustom themselves to an out-door life and to light clothing, have only to reform their eating-habits to make themselves virtually disease proof; while _all_ classes may derive great benefit from a rational application of the principle. That certain symptoms, popularly called cold, are often _excited_ by exposure to fresh air, damp air, draughts, and the like, is true enough; and we should be devoutly thankful for this provision of Nature. But it is likewise true that these “exposures” do not, and can not, _originate_ the disease that _in its exit_ manifests the well-known symptoms. _That_ already exists, and has been for months, perhaps, accumulating in the system; and now, an unusual amount of fresh air in the lungs and in contact with the skin, has so _invigorated the organism_ as to enable it to institute measures for thrusting out the real disease; hence catarrh, cough, expectoration, _fever_——for the name, cold, is a complete misnomer, and based upon a misconception as to the real nature of the disorder: the patient may be never so chilly, but the thermometer placed under the tongue at once shows that the temperature is above the normal standard. Says Dr. Oswald:[13] “Rightly interpreted, the external symptoms of disease constitute a restorative process that can not be brought to a satisfactory issue till the cause of the evil is removed. So that, in fact, the air-hater confounds the cause of his recovery with the cause of his disease. Among nations who pass their lives out-doors, catarrh and scrofula are unknown; not fresh air, but the want of it, is the cause of countless diseases, of fatal diseases where people are in the habit of _nailing down_ their windows every winter to keep their children from opening them. The only objection to a ‘draught’ through a defective window is, that the draught is generally not strong enough. An influx of fresh air into a sick-room is a ray of light into darkness, a messenger of Vishnu visiting an abode of the damned. Cold air,” he continues, “is a disinfectant, and under the pressure of a high wind a modicum of oxygen will penetrate a house in spite of closed windows. This circumstance alone has preserved the lives of thousands whom no cough syrup, or cod-liver oil