Q. What is the fuel of the body?
A. Food is the fuel of the body; and the carbon of the food mixing with the oxygen of the air, evolves heat in the same way that a fire or candle does.
Q. Why is every part of the body warm?
A. As the capillary veins run through every part of the human body, and the combustion of blood takes place in the capillary veins, therefore every part of the body is warm.
Q. Why does running make us warm?
A. When we run, we inhale air more rapidly; and the rapidity with which we inhale air fans the combustion of our body, as a pair of bellows quickens the flame of a common fire.
Q. How does inhaling air rapidly make the body feel warm?
A. As the combustion of the blood is more rapid, (in consequence of the introduction of more oxygen from theair), therefore the blood is more heated, and every part of the body is warmer also.
Q. Why does hard work produce hunger?
A. Because it produces quicker respiration; by which means a larger amount of oxygen is introduced into the lungs, and the capillary combustion increased. Hunger is the notice (given by our body) to remind us, that our food-fuel must be replenished.