The first fundamental principle of sewage disposal, therefore, is to distribute the organic matter in the sewage so that these beneficent bacteria may most rapidly and thoroughly accomplish their purpose. During the last fifty years, a great deal of study has been expended on this problem, and while it has not as yet been entirely solved, certain essential features have been well established. The most important factor promoting the activity of these agents of decay is the presence of air, since in many ways it has been proved that without air their action is impossible. Thus it has been shown that discharging sewage into a stream, whether the stream be a slow and sluggish one or whether it be a mountain stream churned into foam by repeated waterfalls, has little other power to act on organic matter than to hold it for transportation down stream, or to allow it to settle in slower reaches until mud banks have been accumulated which will be washed out again at the first freshet. Experiments have shown that the agencies to which certain diseases are attributed, commonly known as pathogenic bacteria, are frequently, if not always, found in sewage, and that when these bacteria are discharged into streams they may be carried with the stream hundreds of miles and retain all their power for evil, in case the water is used for drinking purposes. No right-minded person to-day will so abuse the rights of his fellow-citizens as deliberately to pour into a stream such unmistakable poison as sewage has proved itself to be. The fact is so well known that it is not worth while pointing out examples. It is enough to say that some of the worst epidemics of typhoid fever which this country has known have been traced to the agency of drinking water, polluted miles away by a relatively small amount of sewage. In a number of states, laws have been passed which expressly prohibit the discharge of sewage, even from a single house, into a stream of any sort, even though the stream is on the land of the man thus discharging sewage and where it would appear as if he alone might control the uses of that stream. Unfortunately, the machinery of the law does not always operate to detect and punish the breakers of the law, but any law which, as in this case, has so positive a reason for its existence, and violation of which is so certain to bring disaster on persons drinking the water of the stream below the point where the sewage is discharged, any law which appeals for its enforcement so directly to the common sense and right feeling of all intelligent people, seems hardly to need legal machinery for its enforcement. It must depend, as indeed all laws must depend, upon the intelligent support of the community, and surely no law would commend itself more urgently than this one forbidding the pollution of drinking water.