34 6 SCIENCE PROGRESS 



operation of the public health authorities in America. In 

 the near future, therefore, we may have the more progressive 

 cities of U.S.A. competing with those of the United Kingdom 

 and Germany, in their efforts to show a low soot-fall and 

 clean atmosphere, as measured by the standard form of 

 apparatus. 



When one sees and notes the great attention given to, and 

 the immense sums of money spent in these days upon, the 

 provision of pure supplies of water and food for our city 

 populations, it is amazing to find that the no less important 

 factor oipure air has been neglected to so great an extent. 



Pure water, pure food, and pure air are, in fact, the three 

 most essential aids in the preservation of good health, and it is 

 satisfactory to find that the importance of the third factor is at 

 last being recognised. 



