The defiant, polluted and oppressive city is condemned for failing to regard the warnings.
The recognition of the dangers accompanying the drinking of polluted water or milk, or of those attached to the breathing of a germ-polluted atmosphere, has been the natural sequence of an improved knowledge of pathology in its bacteriological relationships.
The water supply, deemed ample when the prison was planned, became polluted under the congested conditions.
The extermination of noxious animals, and the exposure of corpses to the dogs and birds, that earth may not be polluted by their presence.
Yet it cannot be too constantly urged that such filtration depends for its comparative perfection upon the surface film; that this surface film is not present when the filter is new, or when its materials have been recently washed; that it may be, and very often is, punctured by the actual working of the filters, or for the purpose of increasing their discharge; and that at the best it must be regarded as an exceedingly thin line of defence, not to be depended upon as a safeguard against highly polluted waters, if a purer source of supply can possibly be found.