ig6 THE POPULAR SCIENCE MONTHLY. 



RELATION OF THE AIR TO THE HOUSE WE LIVE IN.* 



By De. max von PETTENKOFEE, 

 professor of hygiene at tue university of munich. 



WE shall devote this evening to the consideration of some hygi- 

 enic functions of tlie house.^ On the whole, the house has the 

 same hygienic object as our clothing : it has not only to keep up the 

 intercourse with the atmosphei-e surrounding us, but to regulate it 

 according to our wants. No more than our clothing ought the house 

 to be a contrivance for excluding us from the air outside. In some of 

 their forms we can also trace a certain mutual transition. The cloak 

 and the tent are cousins. The heavy circular cloak of former times 

 might well be styled a portable tent, and the tent a fixed cloak ; both 

 have their necessary openings. So the hat may be considered the 

 roof of our clothing, and the roof the head-gear of the house. 



We may then naturally suppose that those materials which are 

 advantageous for the building of our habitations must stand in some- 

 what the same relations to air, water, and heat, as the materials we 

 use for our clothing. Walls allow air to pass through them, and they 

 must do so to a certain degree, if we are to preserve our health within 

 them with some comfort, and without injury. Current opinion 

 is certainly opposed to my assertion about the permeability of walls 

 to air, even more so than to that about the permeability of our 

 clothing ; but it is easy to show that current opinion labors under an 

 error w^hich has no other basis than the insensibility of our senses to 

 the movement of the air, if the same is less than nineteen inches per 

 second. This is the cause of the fallacy that no motion of the air 

 takes place. Just as well might we deny the earth's rotation round 

 its axis at the rate of more than a quarter of a mile per second, be- 

 cause we are not in the least aware of this tremendous velocity. Only 

 very late and slowly have our minds opened to the conviction that 

 after all the earth moves round the sun, and not the sun round the 

 earth, and that our eyes had all the while been mistaken. There 

 must exist something of a higher nature, of a greater power, than our 

 sensuous perceptions, and that is science, which examines and probes 

 our perceptions. Science has not the least power over Nature ; she 

 cannot command any alteration in Nature, cannot give it any laws 



' Abridged and translated by Augustus Hess, M. D., member of the Royal College of 

 Physicians, London, etc. 



2 In England, owing to the manner of building, the smaller size of the houses, the 

 open fireplaces, and the badly-fitting windows and doors, we suffer less from defective 

 ventilation than in Germany ; and, although some other domestic arrangements, though 

 far from faultless, are superior to those usually met with in Germany, nevertheless, the 

 general laws are the same, and ought to be generally understood. Translator. 



