506 



Popular Science Monthly 



breathe through, but when it expands it 

 may become large enough to close up com- 

 pletely the breathing space in that nostril. 

 It was found that warm air, from 80 

 to 90 degrees, has a tendency to make 

 this turbinate bone expand. Warm, 

 moist air is apparently more 

 likely to do this than warm 

 dry air. The man in one 

 of the pictures is breath 

 ing on a cold, shiny 

 metal plate. The 

 moisture in his breath 

 condenses, is turned 

 into water droplets 

 on the plate and 

 makes two little im- 

 pressions whose size 

 gives some idea of the 

 breathing space. The 

 black areas of the chart 

 show that in this case the 

 heated air of the room 

 caused the turbinate bone 

 in one nostril to expand 

 considerably more than 

 that in the other nostril. 

 While this appreciably 

 lessened his breathing 

 space he was not so 

 oppressed by the closeness 

 of the room as he would 

 have been if both nostrils 

 had been affected to the 

 same extent. This fact is of importance 

 because this swollen or congested condition 

 of the turbinates and adjoining membrane, 

 accompanied as it is by increased secretion, 

 has a good deal to do with catching of colds. 

 The physical sensation resulting is like 

 that of a cold in the head. 



Why Even Warm Winds Are Cooling 



The reader may be tempted to inquire 

 why, if heat has such a pronounced effect 

 on the body, we are not all sick in the 

 summer time. The answer is that we are 

 not all sick in the hot summer weather 

 simply because we have means of keeping 

 our bodies cool — as cool or actually cooler 

 than when indoors in the winter time. 



In the first place the body produces less 

 heat in summer. In the second place, we 

 wear lighter weight clothing in summer. 



By reason of the excessively high tem- 

 perature of the air about us in summer — 

 80 to 100 degrees — our bodies are caused 

 to perspire much more freely than is the 

 case in an atmosphere of 70 degrees indoors 



This man's body is exposed to the 

 temperature of one room and his 

 head to that of another. He is breath- 

 ing the air from the first room. The 

 temperature of his head is being 

 taken with an attached thermometer. 

 The experiment determine.-; exactly 

 which part of the body is most af- 

 fected by changes of temperature 



in the winter. Our clothing becomes damp 

 on absorbing this moisture from the skin. 

 Now, when' a current of air passes over a 

 damp cloth it takes moisture away from 

 the cloth : — or causes water to evaporate 

 from the cloth. Heat is used up in 

 converting water or moisture 

 into water vapor. Place a 

 damp cloth on the bulb 

 of an ordinary thermom- 

 eter — the cloth need not 

 be cold — and expose 

 this to a breeze. You 

 will observe that the 

 thermometer imme- 

 diately indicates a 

 lower temperature. 



This is just what 



happens to the bod}-. 



When a breeze — even 



though it be a hot breeze 



— blows across damp skin 



or damp clothes it extracts 



heat. The body is exposed 



more frequently to breezes 



in the summer; for we are 



out of doors more and even 



when indoors we have the 



windows wide open. This 



outdoor air is only very 



slightly purer chemically 



than the cool indoor air of 



winter. It is the cooling 



effect — not, however, cool 



enough to be chilling — which constitutes 



refreshment. The ventilating engineer has 



got to know the causes of "freshness." 



A 



Determining whether a student can do bet- 

 ter mental work in a cool or a warm room 



