The evidence of the effect of drainage in removing the cause of malarial diseases is complete and conclusive. Instances of such improvement in this country are not rare, but they are much less numerous and less conspicuous nere than in England, where draining has been much more extensively carried out, and where greater pains have been taken to collect testimony as to its effects.

If there is any fact well established by satisfactory ex. perience, it is that thorough and judicious draining will entirely remove the local source of the miasm which produces these diseases.

The voluminous reports of various Committees of the English Parliament, appointed to investigate sanitary questions, are replete with information concerning expe rience throughout the whole country, bearing directly on this question.

Dr. Whitley, in his report to the Board of Health, (in 1864,) of an extended tour of observation, says of one town that he examined:

"Mr. Nicholls, who has been forty years in practice "here, and whom I was unable to see at the time of my 66 visit, writes: Intermittent and remittent are greatly on "on the decline since the improved state of drainage of "the town and surrounding district, and more particularly "marked is this alteration, since the introduction of the "water-works in the place. Although we have occasional "outbreaks of intermittent and remittent, with neuralgia attacks, they yield more speedily to remedies, and are "not attended by so much enlargement of the liver or spleen as formerly, and dysentery is of rare occurrence." Dr. Whitley sums up his case as follows:

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"It would appear from the foregoing inquiry, that in"termittent and remittent fevers, and their consequences, "can no longer be regarded as seriously affecting the "health of the population, in many of the districts, in which "those diseases were formerly of a formidable character

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"Thus, in Norfolk, Lincolnshire, and Cambridgeshire, counties in which these diseases were both frequent and 66 severe, all the evidence, except that furnished by the "Peterborough Infirmary, and, in a somewhat less degree, "in Spaulding, tends to show that they are at the present "time, comparatively rare and mild in form."

He mentions similar results from his investigations in other parts of the kingdom, and says:

"It may, therefore, be safely asserted as regards Eng"land generally, that:

"The diseases which have been made the subject of the 66 present inquiry, have been steadily decreasing, both in "frequency and severity, for several years, and this de"crease is attributed, in nearly every case, mainly to one 66 cause,―improved land drainage,” again:

"The change of local circumstances, unanimously de "clared to be the most immediate in influencing the pre"valence of malarious diseases, is land drainage;" and again:

"Except in a few cases in which medical men believed "that these affections began to decline previously to the "improved drainage of the places mentioned, the decrease "in all of the districts where extensive drainage has been "carried out, was stated to have commenced about the "same time, and was unhesitatingly attributed to that

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cause."

A select Committee of the House of Commons, appointed to investigate the condition and sanitary influence of the Thames marshes, reported their minutes of evi dence, and their deductions therefrom, in 1854. The fol. lowing is extracted from their report:

"It appears from the evidence of highly intelligent and "eminent gentlemer of the medical profession, residing in "the neighborhood of the marshes on both sides of the

"Thames below London Bridge, that the diseases preva "lent 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 lo"calities which adjoin imperfectly drained lands, and far "exceed the usual average; and that ague and allied dis"orders frequently extend to the high grounds in the vicin "ity.. 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 protec tion 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 inflam. matory 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.

W. H. Gall, M. D., thought that the extent to which malaria affected the health of London, must of course be very much a theoretical question; "but it is very remark. "able that diseases which are not distinctly miasmatic, do "become much more severe in a miasmatic district. In"fluenzas, which prevailed in England in 1847, were very "much more fatal in London and the surrounding parts "than they were in the country generally, and influenza "and ague poisons are very nearly allied in their effects. "Marsh miasms are conveyed, no doubt, a considerable "distance. Sufficiently authentic cases are recorded to "show that the influence of marsh miasm extends several "miles." Other physicians testify to the fact, that near the Thames marshes, the prevalent diseases are all of them of an aguish type, intermittent and remittent, and that they are accompanied with much dysentery. Dr. John Manly said that, when he first went to Barking, he found a great deal of ague, but since the draining, in a population of ten thousand, there are not half-a-dozen cases annually and but very little remittent.

The following Extract is taken from the testimony of Sir Culling Eardly, Bart.:

"Chairman:-I believe you reside at Belvidere, in the 'parish of Erith ?—Yes.-Ch.: Close to these marshes? "Yes.-Ch.: Can you speak from your own knowledge, "of the state of these marshes, with regard to public "health ?-Sir C.: I can speak of some of the results "which have been produced in the neighborhood, from the "condition of the marshes; the neighborhood is in one

"continual state of ague. My own house is protected, from "the height of its position, and a gentleman's house is less "liable to the influence of malaria than the houses of the "lower classes. But even in my house we are liable to 86 ague; and to show the extraordinary manner in which "the ague operates, in the basement story of this house "where my men-servants sleep, we have more than once "had bad ague. In the attics of my house, where my "maid-servants sleep, we have never had it Persons are "deterred from settling in the neighborhood by the agu"ish character of the country. Many persons, attracted "by the beauty of the locality, wish to come down and 66 settle; but when they find the liability to ague, they "are compelled to give up their intention. I may mention "that the village of Erith itself, bears marks of the influ 66 ence of malaria. It is more like one of the desolate "towns of Italy, Ferrara, for instance, than a healthy, "happy, English village. I do not know whether it is "known to the committee, that Erith is the village describ"ed in Dickens' Household Words, as Dumble-down'deary, and that it is a most graphic and correct descrip"tion of the state of the place, attributable to the unhealthy "character of the locality."

He also stated that the ague is not confined to the marshes, but extends to the high lands near them.

The General Board of Health, of England, at the close of a voluminous report, publish the following "Conclusions as to the Drainage of Suburban Lands:

"1. Excess of moisture, even on lands not evidently wet, "is a cause of fogs and damps.

"2. Dampness serves as a medium for the conveyance of "any decomposing matter that may be evolved, and adds "to the injurious effects of such matters in the air:-in "other words the excess of moisture may be said to increase "or aggravate atmospheric impurities.