If the evils of the pollution of such a stream were much greater, they would still be found inconsiderable as compared with the perpetual pollution of the air by the retention of ordures and refuse amidst large masses of the population. What has been stated as to the practicability of extending threefold the cleansing of towns, by dispensing with cartage, and using the sewers for the removal of the refuse of the streets, is stated as an advantage, even on the supposition that no use is made of the refuse, and that it is entirely thrown away. But it were a reproach to stop at the advance to this far lesser evil, and to add to the pollution of the streams of the towns, which throughout the country form the chief common sewers, by throwing into them everything that is vile in the towns, i. e. everything that is most valuable for increasing the surrounding fertility. On a full examination of the evidence adduced and of the evidence indicated, it will, I trust, be found to be satisfactorily established; that the houses of towns may be constantly and rapidly cleansed of noxious refuse by adaptation of drains and public sewers; and that with such an adaptation, for one street or one district cleansed at the present expense three may be cleansed by the proposed mode; that the natural streams flowing near towns may be preserved from the pollution caused by the influx of the contents of the public sewers, by the conveyance of all refuse through covered pipes, and that the existing cost of conveyance, by which its use for production is restricted, may be reduced to less than one-fortieth or fiftieth of the present expense of removal by hand labour and cartage;[11] that these bounties on cleanliness and salubrity on the one hand, and beneficial production on the other, are dependent on skilful and appropriate administrative arrangements. But for the attainment of these objects, and the relief of the worst-conditioned districts, another provision appears to be requisite, namely, appropriate _Supplies of Water._