Doubtless the true province of a cookery book is to tell how to boil, bake, roast, carve, choose provisions, make dishes and pastry, set out the table, and in a hundred ways work up into palatable wholesomeness the daily food. But having in detail gone through these mysteries, we feel tempted to advance a step, and tell our readers something of the making ready of food, that every hour goes on in the great cookery of nature, and how from field and garden, beef, mutton, milk, and grain, are built up our bulk and strength.

It is curious to note man gathering his sustenance all over the world, how in search of it he fishes and hunts, rears flocks and herds, ploughs, sows and reaps, goes headlong into anxieties, rises early, lies down late, and wears out and renews his strength. There is no land too stubborn for him, no sea too deep, no hill too high, no zone too burning hot or freezing cold, no bird too swift of wing, or beast too wild; roots, plants, fruits, flesh, he has stomach for everything. The Esquimaux, in his six months of frozen night, smacks his lips over his whale blubber; the Samoied, following the chase over hill and dale, in clear dry cold mountain air, eats his eight or ten pounds of meat a-day, and holds a dozen tallow candles, if chance throw them in his way, a rich dessert; the native of Southern India lives on rice and fruit; the European under the same hot sun stirs up his stomach with spices and pickles, to tempt himself to his usual cold climate fare; the wandering Arab for whole months lives upon milk alone, and in view of all the thousand strange simples and messes on which men live, grow, and gather strength, it was long (indeed until quite recently) held, that there was some special miracle of cookery performed in the stomach, by which no matter what came into it was made to feed the blood and build up the bone and muscle.

Every ingredient, and the quantities of it in bone and fat, flesh and sinew, were as well known to men learned in such matters, as the ingredients of any given dish to a cook, but although it, was never thought the cook could furnish up the dish without the right matters to make it, it was held that the stomach could build up the human frame out of food, no matter how short the food might be of the needful ingredients.

Modern discovery has however proved that the stomach can create nothing; that it can no more furnish us with flesh out of food, in which, when swallowed, the elements of flesh are wanting, than the cook can send us up roast beef without the beef to roast. There was no doubt as to the cook and the beef, but the puzzle about the stomach came of our not knowing what matters various sorts of food really aid contain; from our not observing the effects of particular kinds of food when eaten without anything else for some time, and from our not knowing the entire uses of food. But within the last few years measures and scales have told us these things with just the same certainty as they set out the suet and raisins, currants, flour, spices, and sugar, of a plum-pudding, and in a quite popular explanation it may be said that we need food that as we breathe it may warm us, and to renew our bodies as they are wasted by labour. Each purpose needs a different kind of food. The best for the renewal of our strength is slow to furnish heat; the best to give us heat will produce no strength. But this does not tell the whole need for the two kinds of food.

Our frames are wasted by labour and exercise; at every move some portion of our bodies is dissipated in the form either of gas or water; at every breath a portion of our blood is swallowed, it may be said, by one of the elements of the air, oxygen; and of strength-giving food alone it is scarce possible to eat enough to feed at once the waste of our bodies, and this hungry oxygen. "With this oxygen our life is in some sort a continual battle; we must either supply it with especial food, or it will prey upon ourselves; - a body wasted by starvation is simply eaten up by oxygen. It likes fat best, so the fat goes first; then the lean, then the brain; and if from so much waste, death did not result, the sinews and very bones would be lost in oxygen.

The more oxygen we breathe the more need we have to eat. Every one knows that cold air gives a keen appetite. Those who in town must tickle their palates with spices and pickles to get up some faint liking for a meal, by the sea, or on a hill-side, are hungry every hour of the day, and the languid appetite of summer and crowded rooms, springs into vigour with the piercing cold and open air of winter. The reason of this hungriness of frosty air is simply that our lungs hold more of it than they do of hot air, and so we get more oxygen, a fact that any one can prove, by holding a little balloon half filled with air near the fire, it will soon swell up, showing that hot air needs more room than cold.

But the oxygen does not use up our food and frames without doing us good service, as it devours it warms us. The fire in the grate is oxygen devouring carbon, and wherever oxygen seizes upon carbon, whether in the shape of coals in a stove or fat in our bodies, the result of the struggle (if we may be allowed the phrase) is heat.

In all parts of the world, at the Equator and the Poles, amidst eternal ice and under a perpendicular sun, in the parched desert and on the fresh moist fields of temperate zones, the human blood is at the same heat; it neither boils nor freezes, and yet the body in cold air parts with its heat, and just as we can keep an earthenware bottle filled with boiling water, hot, by wrapping it in flannel, can we keep our bodies warm by covering them closely up in clothes. Furs, shawls, and horse-cloths have no warmth in themselves, they but keep in the natural warmth of the body. Every traveller knows that starting without breakfast, or neglecting to dine on the road, he feels more than usually chilly; the effect is very much the same as if he sat to his meals on the same cold day in a room without a fire; the internal fuel, the food, which is the oil to feed life's warming lamp, is wanting. On this account, a starving man is far sooner frozen to death than one with food in his wallet. The unfed body rapidly cools down to the temperature of the atmosphere, just as the grate cools when the fire has gone out. Bodily heat is not produced in any one portion of the body, but in every atom of it.