200 BREATHING AGAINST THE WIND. 



sels which join the arteries to the veins, and also in 

 the small lymphatics, is more impeded there than 

 in the rest of the body. That unnatural resist- 

 ance, of course, causes an unnatural action, and 

 stiff-necks, and other local rheumatic affections, 

 are the consequence. It is matter of common 

 observation, too, that the danger is greatest when 

 one sits with one's back to the draught, and that 

 it is least when the face is turned to it. The fact 

 is, that the draught produces little bad effect, if 

 any at all, if it blow only on the face ; and one 

 can bear to look a whole day out at a window, the 

 draught at which would produce a stiff-neck, or 

 even a cold, if the back were exposed to it for an 

 hour. Now the back of the head and the neck have 

 no means of protection against the effects of the 

 current, except the artificial covering that maybe on 

 them; but there is self-protection in the face. The 

 breath which is expired, is heated in the lungs, 

 and also charged with moisture. As in the opera- 

 tion of breathing, carbon or charcoal, which pre- 

 viously existed in probably a solid state, unites 

 with the oxygen of the inspired air, and with it 

 forms carbonic acid gas, it might be supposed that 

 cold would be the result, as is the case when 

 most substances pass from any more condensed 

 state into the state of gas. Such, however, is not 

 the fact ; otherwise, a common fire would cool the 

 room instead of heating it, and furnaces would 

 harden metals instead of melting them ; for the 

 chief process which goes forward in the burning 

 of fuel, is the conversion of the oxygen of the air 

 and the carbon of the fuel into carbonic acid gas. 

 There are, indeed, generally other matters in the 

 fuel such as hydrogen, which passes off, mixing 

 with oxygen, in flame, and the result is water, 



