A select Committee of the House of Commons, appointed to investigate the condition and sanitary influence of the Thames marshes, reported their minutes of evidence, and their deductions therefrom, in 1854, The following is extracted from their report: "It appears from the evidence of highly intelligent and eminent gentlemen of the medical profession, residing in the neighborhood of the marshes on both sides of the Thames below London Bridge, that the diseases prevalent in these districts are highly indicative of malarious influences, fever-and-ague being very prevalent; and that the sickness and mortality are greatest in those localities which adjoin imperfectly drained lands, and far exceed the usual average; and that ague and allied disorders frequently extend to the high grounds in the vicinity. In those districts where a partial drainage has been effected, a corresponding improvement in the health of the inhabitants is perceptible." In the evidence given before the committee, Dr. P. Bossey testified that the malaria from salt marshes varied in intensity, being most active in the morning and in the Summer season. The marshes are sometimes covered by a little fog, usually not more than three feet thick, which is of a very offensive odor, and detrimental to health. Away from the marshes, there is a greater tendency to disease on the side toward which the prevailing winds blow. Dr. James Stewart testified that the effect of malaria was greatest when very hot weather succeeds heavy rain or floods. He thought that malaria could be carried _up_ a slope, but has never been known to descend, and that, consequently, an intervening hill affords sufficient protection against marsh malaria. He had known cases where the edges of a river were healthy and the uplands malarious. In Santa Maura and Zante, where he had been stationed with the army, he had observed that the edge of a marsh would be comparatively healthy, while the higher places in the vicinity were exceedingly unhealthy. He thought that there were a great many mixed diseases which began like ague and terminated very differently; those diseases would, no doubt, assume a very different form if they were not produced by the marsh air; many diseases are very difficult to treat, from being of a mixed character beginning like marsh fevers and terminating like inflammatory fevers, or diseases of the chest. Dr. George Farr testified that rheumatism and tic-doloreux were very common among the ladies who live at the Woolwich Arsenal, near the Thames marshes. Some of these cases were quite incurable, until the patients removed to a purer atmosphere.