Mention is made, however, of the overcrowding which existed in another large section of the community--namely, the overcrowding of children in some of the schools. The Medical Officer of Health for Whitechapel reported that there was much overcrowding, and in his report for 1857 gave some instances of it in his district:-- 18, _Charlotte Street_.--In a room 8 feet high, 7 wide, 10 long: 14 children and 1 mistress = 37 cubic feet each. 17, _Charlotte Street_.--Matters still worse; the room was underground; 10 feet wide, 10 long; about 7 feet high; 35 children and 1 mistress = 20 cubic feet each. 2, _Gorelston Street_.--672 cubic feet; 31 children and 1 mistress = 20 cubic feet each. In such cases the atmosphere must have been a rapid poison to those breathing it. There was another powerful contributory cause to the general insanitation of London, namely, the defilement of the atmosphere which people had to breathe. As one of the Medical Officers of Health said some years later:-- "We should remember that the air we breathe is as much our food as the solids we eat and the liquids we drink, and as much care should be taken that it is free from adulteration." London was already the greatest manufacturing city in the world, and the great volumes of smoke proceeding from the numerous factories undoubtedly deteriorated the quality of the air. But it was the noxious vapours proceeding from the various processes of manufacture classified as "noxious trades" which rendered the atmosphere in many parts of London dangerous to health. Many were the descriptions given of the almost intolerable evils. Thus the Medical Officer of Health for Rotherhithe reported in 1857:-- "In the mile length of Rotherhithe Street there are no less than nine factories for the fabrication of patent manure, that is to say, nine sources of foetid gases. The process gives out a stench which has occasioned headache, nausea, vomiting, cough, &c. Many complaints have been made by the inhabitants." From St. Mary, Newington, "the terrible effluvium of bone-boiling is freely transmitted over the district." Some manufacture in a yard in Clerkenwell (1856-7), which had existed until lately, was "one of the most abominable, exceeding anything that the imagination could picture." And in every parish or district of London there were slaughter-houses. "There are too many slaughter-houses in crowded districts," wrote the Medical Officer of Health for St. Pancras (1856-7). "It is impossible that slaughtering of animals can be carried on amongst a dense population without proving more or less injurious to the public health. "This it does in several ways--by occasioning the escape of effluvia from decomposing animal refuse into the air and along the drains, and by the numerous trades to which it gives rise in the neighbourhood which are offensive and noxious, such as gut-spinning, tallow-melting, bladder-blowing, and paunch-cleansing."