Mountain air is pure, and removed from miasmata and exhalations, whether from marshes or (being usually sparsely inhabited) men. It is usually still and seldom foggy. The variations of temperature are very great and very rapid, the visitor having often to undergo, within a few hours, a tropical and an arctic climate. These rapid variations serve probably to stimulate vital processes, and there can be little doubt that they are important factors in the general effect produced by mountain climates. The following notes made during a sojourn at Davos in Switzerland may serve to bring some of the above facts in a more concrete form before the reader. “The height above sea-level is between 5000 and 6000 feet, and the barometer stands at about an average of 620 millimètres, instead of 760, which is its average height at the sea-level, so that the weight of the atmosphere is only 620/760, or rather more than three-fourths of what to most of us is its normal weight. The result of this is that under the influence of the sun’s rays evaporation is marvellously rapid. The dew is gone in an instant, and the vapours of the early morning seem to vanish at the first touch of the solar heat. Thus it follows that although the rainfall is considerable, the dryness of the air is, during the main part of the day, nearly absolute. The range of temperature is apt to be very great, and the thermometer, even in the height of summer, is frequently below freezing point in the early morning and in the shade, while in the sunshine, towards midday, the heat is simply scorching. For the most part, however, the temperature is very pleasant in summer; and even invalids, if properly provided with wraps, may spend almost all the hours of daylight out of doors. The obvious results on a healthy person of living in such a climate are (1) a slight increase in the rate of pulse and respiration; (2) a craving for and an ease in performing muscular exercise; and (3) a marked increase of the appetite, with a general feeling of exhilaration. The air acts, in fact, as a powerful stimulant. Ladies, and those who are not able to take much exercise, often have a difficulty in sleeping, but this is never of long continuance. Owing, it is said, to the diminished atmospheric pressure, the cutaneous blood-vessels dilate, and the complexion becomes (with the help of the sun) exceedingly ruddy, a fact which is particularly noticeable in the inhabitants, whose red cheeks strike a stranger with astonishment.”