672 THE POPULAR SCIENCE MONTHLY. 



Since the above was written, the subject has been very graphically 

 presented by means of colored maps, published in the " Keport of the 

 Chief Signal-Officer " for 1884, which maps were compiled at the sug- 

 gestion and earnest solicitation of the Colorado State Medical Society.* 



They show plainly that, in the spring and autumn of 1882, the por- 

 tion of the United States which contained the fewest grains of vapor 

 to the cubic foot of air (viz., 1*5 grain) was the portion of the Rocky 

 Mountain range reaching from near the northern boundary of Wyo- 

 ming to about the center of New Mexico and Arizona ; and that, while 

 during the winter mouths the Northwest, owing to the extreme cold, 

 contained only from 0*5 to 1*0 grain of vapor, that section which we 

 are considering contained the same amount throughout its northern 

 half, while its southern half ranged from 1 to 1*5 grain. During the 

 same winter months the vapor along the California coast is marked as 

 having been 2*5 grains to the foot, and in Florida it was 4 grains in 

 the north and 7 grains at Key West. 



We wish to emphasize this matter of extreme atmospheric dryness, 

 as it not only plays a most important part in a consideration of the 

 climatic cure of consumption, but it is also a prime factor in making, 

 what to an Eastern mind may appear as low temperatures, not only 

 bearable but even comfortable. 



Says Professor Frankland, "The absence of suspended watery 

 particles in the air has, no doubt, very considerable influence in pre- 

 venting the chilling of the skin " ; and this, together with diminished 

 atmospheric pressure — which, the same writer says, makes the air, if 

 still, feel warmer at an elevated station than in lower and denser regions 

 of the atmosphere, " in consequence of the slower abstraction of heat 

 from the body " — these conditions, we say, are the reasons why low 

 temperatures with us do not feel so cold — and, so far as being out of 

 doors is concerned, really are not so cold — as the corresjionding tem- 

 peratures at sea-level. 



The next favorable atmospheric condition mentioned as existing at 

 Davos is the fact that there is a " clear sun," by which, we presume, 

 is meant an absence of clouds and a large amount of sunshine. 



In this connection we have previously called attention to the fact 

 that there are in this climate, on the average, three hundred and twenty 

 sunny days per annum, when the invalid can be out of doors. In 

 other words, our cloudy days, as interpreted by the Signal Service 

 — i. e., days when the heavens are from seven tenths to ten tenths ob- 

 scured by clouds at 7 a. m., 3 and 11 p. m., Washington time — our 

 cloudy days average only forty-six, while in New York they average 

 one hundred and nine, at Jacksonville eighty-seven, and at St. Paul 

 one hundred and four per annum. 



This fact also has been graphically portrayed by another series of 



* As a member of the committee from that society, intrusted with the matter, wc take 

 pleasure in acknowledging the courteous attention our request received. 



