Perhaps I need not inform you that indigestion, with all that follows from it, is so frequent in the metropolis, in persons after the first strength of youth, that, for large classes of society, a perfect discharge of the natural process of digestion (such a discharge of it as a lecturer would describe to be the exact type and intention of Nature), is exceptional and rare. Unquestionably, in large numbers of cases, wine and beer and spirits, rather than water, have to do with this effect. Unquestionably, other influences of metropolitan life--and, not least, the mental wear and tear which belong to its large excitement, contribute immensely to this chronic derangement of health; but there are reasons likewise for believing, that the quality of water consumed is not a matter of indifference to the result. We cannot but give it an important place among those influences of health or unhealth which we consider _local_; and we cannot refuse to recognise the fact, that in recommending our patients (as we do often recommend them) to try ‘change of air’ for complaints which baffle us by their obstinacy, so long as the subject of them remains in London, the course on which we rely for success implies ‘change of water,’ equally with that other change to which more popular importance is attached. In illustration of this view, I may quote to you the experience of two other towns. Dr. Sutherland stated, in evidence before the General Board of Health, that having lived for a number of years at Liverpool (where the water is said to be of about the same degree of hardness as ours), he had long entertained a conviction that ‘the hard water, in a certain class of constitutions, tends to produce visceral obstructions; that it diminishes the natural secretions, produces a constipated or irregular state of the bowels, and consequently deranges the health. He had repeatedly known these complaints to vanish on leaving the town, and to re-appear immediately on returning to it, and it was such repeated occurrences which fixed his attention on the hard selenitic water of the new red sandstone as the probable cause, as he believed it to be, of these affections.’ (Rep. p. 51). And Dr. Leach, of Glasgow, stated before the same Board, as the result in that town of two years’ experience of a substitution of soft for hard drinking-water, that in his opinion, ‘dyspeptic complaints had become diminished in number;’ and that it had ‘been observed, since this change, urinary diseases have become less frequent, especially those attended by the deposition of gravel.’