Q. _Why have persons who follow SEDENTARY PURSUITS less APPETITE 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 APPETITE?_ 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 replenishing_. 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 passionately 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?_ A. 1st--Because they _deprive the blood of carbon_, which is the chief cause of animal heat: and 2ndly--These gases coalesce into _water_, which greatly tempers the animal heat. Q. _Why do we feel LAZY and averse to activity in very HOT WEATHER?_ A. 1st--Because muscular activity would increase the heat of the body, by _quickening the respiration_: and 2ndly--The food we eat in hot weather, _not being greasy_, naturally abates our desire for bodily activity.