THE AIR OF TOWNS. 385 



of dust from the streets of Paris was found to be 84,240, nearly double 

 that contained in similar dust obtained on the outskirts of the town. 



Can we be astonished at finding domestic dust nearly as pregnant 

 with living matter as that from the street, which, according to Miquel, 

 is 64,000 in the grain? It might appear judicious to keep our windows 

 closed under such a siege, but a moment's reflection will, I think, solve 

 the difficulty. We do not know to what degree these microbes are 

 mischievous. We do know to what extent fresh air is necessary to 

 health. Let us admit air, but keep our dwellings, as far as possible, 

 free from dust. Microbes settle rapidly in still air, and we have only 

 to rise a few hundred feet above the ground level to prove it. On the 

 same day Miquel found on the top of the Pantheon less than 1 on 

 the average in the cubic foot; at Montsouris 1£, and in Paris streets 

 about 12. At a height of almost 1,000 feet the number is about one- 

 sixteenth of that on the ground level. On the high Alps, as Pasteur 

 and Tyndall have shown, they disappear completely. If we want fresh 

 air we know where to go. We must climb the hilltops. An idea of 

 the great army of microbes which are constantly on the march out of a 

 big town may be gathered from the number computed for Paris, viz, 

 40,000 million daily, a number which may be graphically expressed 

 by supposing all the microbes in 11 gallons of soup, in full putrefac- 

 tion, to arise and march away. 



Ladies and gentlemen, my task is at an end. There is much that I 

 have left unsaid in the course of these lectures. I should like to have 

 . alluded to the possibility of reducing domestic smoke, of the smoke of 

 our warehouse and office buildings, of the better utilization of coal, and 

 of the use of gas for household purposes. I should like to have said 

 much more on the important subject of ventilation of our dwelling 

 rooms and offices. These matters must be left for a possible future 

 occasion. I should, however, be content with the result of these four 

 lectures if you carried away, immovably impressed upon your minds, 

 the fact that pure air is indispensable to health. Do not let us resem- 

 ble people sitting in a close room who, by gradually becoming accus- 

 tomed to their surroundings, grow oblivious to the polluted atmosphere 

 they are breathing and the poison which they are slowly absorbing. 



A chairman at a lecture which I once delivered on a similar topic to 

 this said at the close: U I think the lecturer makes too much of these 

 invisible things in the air. We seem to keep alive in spite of them." 

 But we don't want merely to keep alive. We want to live without the 

 burden of trying to keep alive. What future is there for a country 

 two-thirds of the population of which inhabit towns, and of whom Mr. 

 Acland said " a great deal of this work of the towns, which necessi- 

 tated strong and healthy men, was done by those who had been brought 

 up in country homes and not in those of towns." 



kAs I have already said, impure air, no matter whether it arises from 

 bad gases, soot, or disease germs, is injurious to health. If we are 

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