384 THE POPULAR SCIENCE MONTHLY 



in the sand, or carved out of clay frightening demons, and so beguiled 

 from the first five the larger share of their wealth. In this land of 

 factories, while the many are confined to mean streets and wretched 

 houses, possessing no sufficiency of baths and clean clothing, and are 

 ill-fed, they work all day long, not to fashion for themselves better 

 houses and clothing, but to make those unnecessaries such as "the 

 fluff" of women's apparel and a thousand trifles which relieve the 

 monotony of the idle and bemuse their own minds. 



The discovery of radium and its disintegration as a source of 

 energy has enabled the physicist to extend Lord Kelvin's estimate of 

 the world's age from some thirty to a thousand million years. Arthur 

 Keith does not hesitate to give a million of these years to man's evolu- 

 tion. Karl Pearson speaks of hundreds of thousands of years. The 

 form of the human skull, the brain capacity of man, his skill as evi- 

 denced by stone implements and cave drawings of animals in action, 

 was the same tens of thousands of years ago as now. For ages primi- 

 tive man lived as a wild animal in tropical climes, discovered how to 

 make fire, clothe himself in skins, build shelters, and so enable himself 

 to wander over the temperate and arctic zones. Finally, in the last few 

 score of years, he has made houses draughtless with glass windows, 

 fitted them with stoves and radiators and every kind of device to pro- 

 tect himself from cold, while he occupies himself in the sedentary pur- 

 suits and amusements of a city life. How much better, to those who 

 know the boundless horizon of life, to be a frontiers-man and enjoy the 

 struggle, with body hardened, perfectly fit, attuned to nature, than to 

 be a cashier condemned to the occupation of a sunless, windless pay- 

 box. The city child, however, nurtured and educated in confinement, 

 knows not the largeness and wonders of nature, is used to the streets 

 with their ceaseless movement and romantic play of artificial light after 

 dark, and does not need the commiseration of the country mouse any 

 more than the beetle who lives in the dark and animated burrows of his 

 heap. But while outdoor work disciplines the body of the countryman 

 into health, the townman needs the conscious attention and acquired 

 educated control of his life to give him any full measure of health and 

 happiness. 



Experimental evidence is strongly in favor of my argument that 

 the chemical purity of the air is of no importance. Analyses show 

 that the oxygen in the worst-ventilated school-room, chapel or theater 

 is never lessened by more than 1 per cent, of an atmosphere; the ven- 

 tilation through chink and cranny, chimney, door and window, and the 

 porous brick wall, suffices to prevent a greater diminution. So long 

 as there is present a partial pressure of oxygen sufficient to change the 

 hemoglobin of the venous blood into oxyhemoglobin there can arise no 

 lack of oxygen. 



