1874.] Thermometric Observations in the Alps. 327 



consequently less abstraction of heat from the body. It also secures 

 greater transcalency in the atmosphere by a position above the chief region 

 of aqueous precipitation, and which is comparatively out of the reach of 

 the dust and fuliginous matters that pollute the lower stratum of the 

 air. On my journey from London to Davos I never saw the sun until I 

 had arrived nearly at my destination ; and during the greater portion of 

 the fortnight of brilliant weather recorded above, there was a dull leaden 

 sky at Zurich, about 60 miles distant. 



2. Thick and (during the winter months} permanent snow, which reflects 

 the solar heat and prevents the communication of warmth to the air, and 

 consequently the production of atmospheric currents. In still, though 

 cold, air the skin is well known to be less chilled than in much less cold 

 air, which impinges with considerable velocity upon the surface of the 

 body. The effect of motion through the air upon the sensation of warmth 

 and cold at Davos is very striking. Sitting perfectly still in the sunshine, 

 the heat in mid winter is sometimes almost unbearable ; on rising and 

 walking about briskly, a delicious feeling of coolness is experienced ; but 

 on driving in a sledge, the cold soon becomes painful to the unprotected 

 face and hands. 



3. A sheltered position favourable for receiving loth the direct and re- 

 flected solar rays. In this respect Davos-Dorfli, situated opposite to the 



entrance of the Dischma valley, has the advantage over Davos-Platz, two 

 miles lower down the valley ; for, in the latter village, the sun rises on 

 the 21st December l h 9 ra later, and sets about ten minutes earlier, than at 

 Dorfli. 



All these conditions contribute not only to a high sun-temperature 

 during the winter months, but also to a comparatively uniform radiant 

 heat from sunrise to sunset. 



In conclusion I will only point to the general bearing which these ob- 

 servations have upon winter refuges for invalids. While the primary 

 conditions to. be secured in such places must ever be fine weather and a 

 sheltered position, the next in importance is, undoubtedly, exposure all 

 day long to reflected, as well as direct, solar radiation. To accomplish 

 this, a southern aspect and a considerable expanse of water, or nearly 

 level snow, are necessary ; and it is important that the sanitarium should 

 be considerably, and somewhat abruptly, elevated above the reflecting sur- 

 face, so that it may receive, throughout the entire day, the uninterrupted 

 reflection of the sun's rays. At the sea-side, for instance, only those 

 houses which command such an uninterrupted view of the sea, ranging 

 from S.E. to S.W., as shows the reflection of the sun throughout the 

 entire day, enjoy the full advantages of the place. At, or near, the sea- 

 level, however, it is impossible, owing to the suspended matters in the 

 lower regions of the atmosphere, to enjoy any thing approaching to a 

 uniform temperature from sunrise to sunset. For this purpose it is 

 necessary to leave the grosser air of the plains behind, and to ascend 



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