=Filtration.=--The following is a simple home-made filter. Take a large flower-pot, and soak it thoroughly in clean water. Stop up the hole in the bottom with a cork, in which insert a glass tube about three or four inches long. The top of the cork and tube should be nearly flat with the inside bottom of the pot. Put in a layer of sharp, clean sand about two inches deep, then two inches of small gravel, and three inches of well-burnt animal charcoal. On the top of this another layer of sand, and then another layer of gravel. The gravel, sand, and charcoal should be thoroughly washed before using. If the flow of water is too rapid, it may be checked by laying several flat pieces of glass upon the layers of sand. At reasonable intervals, the sand, gravel, and charcoal must be taken out, washed thoroughly, heated in the oven, and replaced in the pot, which must also be soaked in boiling water. This filter will remove nearly or quite all of the inorganic matter held in suspension in the water, but it is not to be depended upon to remove dangerous microbes and other germs of disease. If the water be thoroughly boiled for half an hour and cooled before being filtered, all danger will be removed. There are many inexpensive filters on the market. They all become clogged, in a little while, and need to be cleaned or renewed. The cleaning of the one described above is so simple that any housekeeper could do it satisfactorily. FOOD AND DRINK =Why We Eat.=--During the early period of life, and until we reach maturity, food is necessary not only to repair the daily waste, but for the nurture and growth of the body. The intense bodily activity of childhood is attended with a large consumption of material and a great amount of waste. The food is converted into blood, which circulates through the arteries of the body, carrying the nutritive particles to the remotest parts, and returns through the veins, conveying the waste and worn out matter to be expelled from the system. =Quantity of Food.=--Placing the average weight of an adult man at one hundred and forty-four pounds, the average daily amount of food and drink needed would be six pounds, or about one-twenty-fourth the weight of his body. Food should be taken in sufficient quantity to repair the waste, and no more. Most persons habitually eat and drink more than they need, while a few eat less than they should. Those who lead very active lives, or live much in the open air, require more food than the old, the inactive, and the sedentary. Habit, too, has much to do with the quantity of food taken. Over-indulgence in eating is the fruitful cause of a long train of evils. The appetite is pampered by tempting viands, and the stomach is overtaxed with work. The sensation of hunger is Nature’s demand for food; the lack of such sensation should suggest abstinence.