A glance at the table shows that in every district to which the supply of the Southwark and Vauxhall, or the Lambeth Water Company extends, the cholera was more fatal than in any other district whatever. The only other water company deriving a supply from the Thames, in a situation where it is much contaminated with the contents of the sewers, was the Chelsea Company. But this company, which supplies some of the most fashionable parts of London, took great pains to filter the water before its distribution, and in so doing no doubt separated, amongst other matters, the greater portion of that which causes cholera. On the other hand, although the Southwark and Vauxhall and the Lambeth Water Companies professed to filter the water, they supplied it in a most impure condition. Even in the following year, when Dr. Hassall made an examination of it, he found in it the hairs of animals and numerous substances which had passed through the alimentary canal. Speaking of the water supply of London generally, Dr. Hassall says:— “It will be observed, that the water of the companies on the Surrey side of London, viz., the Southwark, Vauxhall, and Lambeth, is by far the worst of all those who take their supply from the Thames.”[13] In the north districts of London, which suffered much less from cholera than the south districts, the mortality was chiefly influenced by the poverty and crowding of the population. The New River Company having entirely left off the use of their engine in the city, their water, being entirely free from sewage, could have had no share in the propagation of cholera. It is probable also, that the water of the East London Company, obtained above Lea Bridge, had no share in propagating the malady; and that this is true also of the West Middlesex Company, obtaining their supply from the Thames at Hammersmith; and of the Grand Junction Company, obtaining their supply at Brentford. All these Water Companies have large settling reservoirs. It is probable also, as I stated above, that the Chelsea Company in 1849, by careful filtration and by detaining the water in their reservoirs, rendered it in a great degree innocuous. Some parts of London suffered by the contamination of the pump-wells in 1849, and the cholera in the districts near the river was increased by the practice, amongst those who are occupied on the Thames, of obtaining water to drink by dipping a pail into it. It will be shown further on, that persons occupied on the river suffered more from cholera than others. Dr. Baly makes the following inquiry in his Report to the College of Physicians.[14]