In the case of diseases, such as typhoid, which attack the stomach, disease germs are removed along with the excreta; and if, as is often the case, the drainage of an infected town flows into a river, and that river is used in some after portion of its course as a water supply, there is great danger of such diseases being communicated. For, however well the water may be purified and filtered, we have no guarantee that it will not contain some of these disease germs, which are so small that they pass through the finest filters. It is in this way that almost all the great cholera and typhoid epidemics have spread.--_Chambers's Journal_. _Well Water Often Dangerous_.--A densely crowded population soon impregnates the soil to some depth with filth, which drains into the water course below, especially if such water is near the surface. This surface water easily penetrates a loosely walled well. Every well, therefore, should not only be widely separated from barnyards, cesspools, pens, sinks, and similar places, but should be made water-tight with cement, so that nothing can reach its interior except water that has been filtered through dense beds of unpolluted ground below. If these precautions are neglected, the best and deepest well may become continually contaminated by infiltration from the surrounding surface. This impure water, even when not used for family drinking, is sometimes supplied to cows, or used for washing dairy pans, or employed in diluting milk for the market, and there are many known cases in which disease has thus been disseminated. Thus, an epidemic of typhoid fever in Cambridge, Mass., was definitely traced to a dairy which supplied the victims with milk. Upon investigation it was found that a short time before there had been a typhoid patient in the farmhouse, and that the well from which water was taken to wash the milk pans had become contaminated with the specific poison brought into it from the surrounding drainage. All suspected water should be thoroughly boiled before using it to drink. Some physicians insist that the boiling should continue for one or two hours in order entirely to destroy the bacterial germs. The heaviness and insipidity incident to boiled water may be somewhat relieved by afterward filtering it. Filtering, of itself, however, will do little toward ridding the water of microbes, which are much too minute to be arrested by the ordinary apparatus.--When journeying, where one must often take a hasty meal at a railway station, drink hot water in preference to cold. A convenient portable filter may be arranged with a bottle of powdered charcoal, and a piece of filtering paper. A traveler by briskly stirring a tablespoonful of the charcoal into a pint of water, allowing it to stand five or ten minutes, and then filtering it through the paper, may venture to relieve his thirst in almost any part of the country.