1907] Climate ix Relation to Health 43 



wish not only to maintain health but also to reconstruct diseased 

 tissues, that we have not only an abundant supply of pure 

 oxygen, but also food to restore tissues, or to make new blood 

 and more heat and energy. 



Humidity of the Atmosphere. It has already been stated that 

 oxygenof the air is to nitrogen as 1 to 4 in volume. But we have in 

 the atmosphere water as vapor in varying amounts. Normal 

 air on a bright day in this climate contains about 70 to 

 75% of saturation with water vapour. All are aware how 

 depressing a damp day is. We say the air is 'heavy,' but as a 

 matter of fact the barometer shows it is lighter. This physical 

 effect means simply that with excessive moisture the air breathed 

 with each respiration has less of oxygen, and we are not then 

 receiving enough to supply the demands of the body tissues, 

 and so they are being over-loaded with effete matter. Moreover, 

 the excessive air moisture prevents our bodies from throwing 

 off body wastes by evaporation. 



Temperature of the Atmosphere. But there is yet another 

 factor of importance in our climate which effects us, that 

 is the coldness of the air. Remembering that air expands 

 1-2 73 part of its volume with every degree F. it is 

 plain that air at zero is, as we may sa3% more condensed, 

 that is every IS cubic inches which we inhale contains more 

 oxygen than at 90 degrees by about 25%. But air at zero holds 

 less than 1 grain of inoisture as vapor, so that cold air inhaled 

 means increased chemical action in the tissues ; more combus- 

 tion, more wastes produced, more waste thrown oft' and more 

 desire for food. 



Regnault's Tables show air at 70 degrees to actually hold 

 7.992 grains of moisture, or 16 times as much as at zero; so that 

 cold, dry air means that the body throws off by both respiration 

 and evaporation much more moisture and w^ith it more wastes 

 from the body in solution. This same condition is attained 

 in the high, dry climate of our western foot-hills, where with a 

 relative humidity of often 50%, the amount of moisture actually 

 cast oft" in twenty-four hours is, according to Dr. Denison, 25% 

 more in twenty-four hours. 



Sunlight. But while the consumption ofoxygen is greater in 

 such climates, and the increased wastescastoff with moisture are 

 likewise increased, we have further another influence in the 

 effects of the direct sunHght of the plains and in our own climate 

 on bright days. Much has of late been told us regarding the 

 actinic rays of the sunlight, these being those at the farthest 

 end of the spectrum, vis., the red and ultra violet. These rays 



