The districts supplied by the Chelsea Company have suffered a much greater mortality, during the recent epidemic, than the average of the whole metropolis, as the subjoined table (No. XIII) shows. But the mortality in these districts is only half as great as in the houses supplied by the Southwark and Vauxhall Company, who obtain their supply from the Thames just opposite the spot where the Chelsea Company obtain theirs. The latter company, however, by detaining the water in their reservoirs, and by filtering it, are enabled to distribute it in a state of comparative purity; but I had ample opportunities of observing, in August and September last, that this was far from being the state of the water supplied by the Southwark and Vauxhall Company. Many of the people receiving this latter supply were in the habit of tying a piece of linen or some other fabric over the tap by which the water entered the butt or cistern, and in two hours, as the water came in, about a tablespoon of dirt was collected, all in motion with a variety of water insects, whilst the strained water was far from being clear. The contents of the strainer were shown to me in scores of instances. I do not, of course, attribute the cholera either to the insects or the visible dirt; but it is extremely probable that the measures adopted by the Chelsea Company to free the water from these repulsive ingredients, either separated or caused the destruction of the morbid matter of cholera. It is very likely that the detention of the water in the company’s reservoirs permitted the decomposition of the cholera poison, and was more beneficial than the filtering, for the following reasons. The water used in Millbank Prison, obtained from the Thames at Millbank, was filtered through sand and charcoal till it looked as clear as that of the Chelsea Company; yet, in every epidemic, the inmates of this prison suffered much more from cholera than the inhabitants of the neighbouring streets and those of Tothill Fields Prison, supplied by that company.[18] In the early part of August last, the use of the Thames water was entirely discontinued in Millbank Prison, and water from the Artesian well in Trafalgar Square was used instead, on the recommendation of Dr. Baly, the physician to the prison. In three or four days after this change, the cholera, which was prevailing to an alarming extent, entirely ceased. =TABLE XIII.=