CHAPTER XIII 



THE MOST NECESSARY BUT LEAST APPRECIATED MA- 

 TERIAL USED IN JACK'S HOUSE PURE AIR 



IN a previous chapter we read that food, air, and 

 water are the materials with which Jack's Wonderful 

 House builds itself. Of these air is no doubt by far 

 the least appreciated. For instance, when a picnic 

 is planned, how carefully every part of the lunch is 

 looked after, but how rarely the air of the crowded 

 cars or of the place to be visited is even considered. 

 If an evening party or banquet is being arranged, 

 much thought is given to the menu, but provision for 

 an abundance of pure air for each guest is often entirely 

 forgotten. 



It is certainly correct to estimate our need of a sub- 

 stance by our dependence on it. Let us compare 

 air and food from this standpoint. Of which do we 

 use the more ? The air we breathe weighs many times 

 as much as the food we eat. Which can we do without 

 the longer? Any one can go without food a day or 

 more and not feel any great discomfort, and persons 

 have been known to fast for even thirty or forty days. 

 At the most, one could exist only a few moments 



H 97 



