54 PERFECT ADJUSTMENT. 



and to eflfect all the known and unknown changes necessary to 

 fit it to cany new life, and heat, and vigour to every part of the 

 body. Every particle of Itlood is made to meet the fresh 

 air, not only without cooling it, but heating it in the process, 

 and heating: it most when the air introduced is coldest. Havinu' 

 been thus fitted for its work, the blood goes back to the heart, 

 entering it now on the left side, and is immediately pumped into 

 the arteries which carry it all over the system, delivering the 

 required quantity as fresh and pure at the feet as at the heart 

 itself, pulling down and building up, wherever and whatever is 

 necessary, carrying nerves, brain, muscles, hair, hoofs, skin, or 

 bones, through vessels too small to carry water, and flowing into 

 the veins comes back again to the right side of the heart to be again 

 passed through the warming and purifying fire in the lungs. 

 All this is done so rapidly that the whole of the blood in the body 

 passes through the heart in a time varying from one to three 

 minutes, and the faster it is kept going by reasonable exercise 

 the more completely does it accomplish its work. 



107. — What we call fire is the rapid combination of carbon 

 with oxygen. Wherever this combination takes place, either 

 quickly or slowly, heat is produced in exact proportion to the 

 amount of carbon and oxygen mixed together. We see it going 

 on in our hearth fires fast enough to produce a destructive flame, 

 and still faster in the smith's fire, where the oxygen is rapidly 

 forced into contact with the carbon by the smith's ])ellows. The 

 same thing goes on slowly in the lungs, restrained and regulated 

 by a strictly limited supply of oxygen. One principal reason 

 whv the blood is heated most in cold Aveather is because cold air 

 lies in less compass than warm air, so that the same pipes can 

 convey more of it, and consequently more oxygen at each 

 inspiration. 



108. — Thus the lungs are a wonderful self regulating furnace 

 that warms the blood just as much and no more thaii is needed, 

 whilst the warm blood by its rapid circulation through a 

 beautiful system of pipes warms every inch of the body, and 

 with the help of a good, healthy, clean skin, will jireserve a 

 uniform temperature of about 100 degrees, whether surrounded 



