A Guide To The Scientific Knowledge Of Things Familiar Part 20

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 the air_), 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_.

Q. _Why does SINGING make us HUNGRY?_

A. Singing _increases respiration_; and as _more oxygen_ is introduced into the lungs, _our food-fuel is more rapidly consumed_.

Q. _Why does READING ALOUD make us feel HUNGRY?_

A. Reading aloud _increases respiration_; and as _more oxygen_ is introduced into the lungs, _our food-fuel is more rapidly consumed_.

Q. _Why do we feel MORE HUNGRY in the DAY-TIME than in the NIGHT-TIME?_

A. As we _breathe more slowly during sleep_, therefore, less _oxygen_ is introduced into the lungs _to consume our food-fuel_.

Q. _Why do we need WARMER CLOTHING by NIGHT than by DAY?_

A. 1st--Because the _night is generally colder_ than the day.

2ndly--As our _respiration is slower_, our _animal combustion is slower also_; in consequence of which, _our bodies are more cold_.

Q. _Why do we PERSPIRE when very HOT?_

A. The pores of the body are _like the safety valves of a steam-engine_; when the heat of the body is too great, the combustible gas and grease _flow out in perspiration_, instead of _burning in the blood_.

Q. _Why do persons feel LAZY and averse to exercise, when they are HALF-STARVED or ILL-FED?_

A. _Animal food_ contains great nourishment, and produces a desire for _active occupations_; but when the body is not supplied with strong food, this desire for muscular action _ceases_, and the person grows slothful.

Q. _Why have persons, who follow HARD OUT-OF-DOORS OCCUPATIONS, more APPEt.i.tE than those who are engaged in SEDENTARY pursuits?_

A. Hard bodily labour in the open air _causes much oxygen to be conveyed into the lungs by inspiration_; the combustion of the food is carried on quickly; _animal heat increased_; and need for nutritious food more quickly indicated _by craving hunger_.

Q. _Why have persons who follow SEDENTARY PURSUITS less APPEt.i.tE than ploughmen and masons?_

A. 1st--The air they inhale _is not so pure_, because its oxygen is partly exhausted: and

2ndly--Their respiration is neither _so quick nor strong_, and therefore the combustion of their food is carried on more slowly.

Q. _Why do we like strong MEAT and GREASY food when the WEATHER is very COLD?_

A. Strong meat and grease contain large portions of _hydrogen_, which (when burned in the blood) produce a larger amount of heat than any other kind of food.

Q. _Why do persons EAT MORE food in COLD weather, than in hot?_

A. In _cold_ weather the body requires more fuel _to keep up the same amount of animal heat_; and as we _put more coals on a fire on a cold day_ to keep our _room warm_, so we _eat more food on a cold day_ to keep our _body warm_.

Q. _Why does COLD produce HUNGER?_

A. 1st--The air contains more _oxygen_ in cold weather; and as _fires burn fiercer_, so _animal combustion is more rapid_: and

2ndly--We are more _active_ in cold weather; and increased respiration acts _like a pair of bellows_ on the capillary combustion.

Q. _Why does rapid DIGESTION produce a craving APPEt.i.tE?_

A. This is a wise providence to _keep our bodies in health_; in order that the _body itself_ may not be consumed, it gives notice (by hunger) that the _capillary fires need replenis.h.i.+ng_.

Q. _Why do we feel a desire for ACTIVITY in cold weather?_

A. 1st--Because activity increases the warmth of the body, _by fanning the combustion of the blood_: and

2ndly--The _strong food_ we eat creates a desire for muscular exertion.

Q. _Why are the Esquimeaux so pa.s.sionately fond of TRAIN OIL and WHALE BLUBBER?_

A. Oil and blubber contain a very _large amount of hydrogen_, which is exceedingly combustible; and as these people live in climates of intense cold, the heat of their bodies is increased by the _greasy nature of their food_.

Q. _Why do we feel a dislike to strong meat and greasy foods in very hot weather?_

A. Strong meat and grease contain so much _hydrogen_, that they would make us _intensely hot_; and therefore we refuse them in hot weather.

Q. _Why do we like fruits and vegetables so very much in hot weather?_

A. Fruits and vegetables contain _less carbon_ than meat, and therefore produce _less blood_: instead of blood, _they combine into water_ as they are digested, and keep the body cool.

Q. _Why do people say that FRUITS and VEGETABLES COOL the BLOOD?_