THE HABITATION AND THE ATMOSPHERE. 169 



marries or dies. He is an obscure man. He may grumble sometimes 

 to his wife, but he does not frequent the grocery, and he does not talk 

 politics at the tavern. So he is forgotten. Yet who is there whom 

 the statesman, economist, and social philosopher, ought to think of 

 before this man ? If any student of social science comes to appreciate 

 the case of the Forgotten Man, he will become an unflinching advocate 

 of strict scientific thinking in sociology, and a hard-hearted skeptic as 

 regards any scheme of social amelioration. He will always want to 

 know, Who and where is the Forgotten Man in this case, who will 

 have to pay for it all ? 



"Certainly there is no harder thing to do than to employ capital 

 charitably. It would be extreme folly to say that nothing of that 

 sort ought to be done, but I fully believe that to-day the next most 

 pernicious thing to vice is charity in its broad and popular sense." 



- 



THE HABITATION" A1STD THE ATMOSPHEKE. 



By M. R. RADAU. 



IN a former article we endeavored to elucidate some of the princi- 

 ples which have been developed from the later researches and ex- 

 periments on the relations of our clothing with the atmosphere (see 

 "Popular Science Monthly," October, 1883). The house, also, may 

 be regarded as a kind of clothing, as a large and ample garment, 

 designed to regulate our relations with the surrounding medium, 

 and to deliver us from its tyranny, but not to isolate us. It ought 

 not to deprive us of air, though that point is too often forgotten. 

 Fortunately, no voluntary prison is so tightly calked up that air 

 from out-of-doors does not find entrance without our perceiving it. 

 The fact that water will readily penetrate a wall or ceiling is known 

 to all, for they can see the spots it makes ; but the air that passes 

 through walls is not seen, and so we imagine that it does not penetrate 

 them. This is a mistake. Walls would not prevent us from being in 

 communication with the outside air, even if no cracks were left around 

 the doors and windows. If water can find a way through them, what 

 is to hinder a subtile gas from doing the same ? The porosity of walls 

 is very far from being an evil ; and we shall shortly see that it is ne- 

 cessary to prevent houses being damp. 



A very simple experiment by Dr. Pettenkofer illustrates the per- 

 meability of building materials. He took a cylinder of dry mortar 

 twelve millimetres (4*7 inches) long and one third as thick, and waxed 

 all of it except the ends, in which he fastened two glass funnels, one 

 of which was extended by an India-rubber tube, while the other ter- 

 minated in a very fine orifice. Blowing through the India-rubber 



