Vegetation, heat, and moisture: these are the three active agents in the production of miasma, to which a fourth is to be added, in the influence of non-drainage, either by the way of the atmosphere or running water. The strongest example of a malarious locality one might make would be in suggesting a marshy valley in a tropical climate, so overrun with fixed water as to destroy a prolific vegetation, yet not covering it enough to protect the garbage from the putrefying influences of the sun; this valley, in turn, so environed with hills as to shut off a circulation of air....Ground newly broken is not unapt to generate miasm. This results from the sudden exposure of long-buried vegetable matter to the influences of moisture and heat....It may readily be conceived that malarious situations exist where the miasm is not sufficient in quantity to produce the effects of intermittent or bilious fever, yet where there is quite enough of it to keep a man feeling good for nothing,--he is not sick, but he is never well. I know of one country seat of this kind, where forty thousand dollars would not pay for the improvements put upon it, and where, I am free to declare, I would not think of living, even if, as an inducement, a free gift were made to me of the place....Besides miasm, there are other atmospheric associations to be considered. I recall this moment a distillery, where attempt was made to get clear of the mash by throwing it into a running stream, with the anticipation of its being carried to the river, but where, on the contrary, it became a stagnant putrescent mass, impregnating the air for miles with its unendurable odor, and inducing such a typhoid tendency that half the countryside were down with fever....There are, again, situations where the filth and debris of sewage exercise a poisoning influence on the surrounding atmosphere. This has its principal application to the neighborhood of cities and towns drained into adjoining streams. London and the Thames furnish a notable illustration. A cove, attractive as it is, may prove a receptacle for the accumulation of dead fish and other offal, which shall make untenable the charming cottage upon the bank. A deep cove has rarely healthy surroundings, the circulation of its water being too sluggish to insure freshness and vitality. Water, like blood, to be healthy, must be in a state of continuous movement. A nonobservant man, purchasing a beautiful stream, may be completely disappointed by finding that the opacity of its water depends upon a factory, of which he had never so much as heard; he may not let his children bathe in it, for he may well fear for them the fate of the fish he so plentifully finds lying dead upon the shore. A poisoned rural stream is as sad a sight as it has grown to be a common one. Always, before buying water, know what there is up stream, or what there is likely to be.