With the marvellous industrial developments of the time, trade, and commerce, and businesses of various kinds and sorts were spreading over a wider area, and constantly claiming accommodation to carry them on; and the process continued of the conversion of residential houses into offices and shops and warehouses and workplaces. The increase of houses in other parts of London, rapid as it was, barely kept pace with the increase of population, whilst it had practically done nothing as yet to relieve overcrowding in the central parts of London. The excessive density of the population was a great sanitary evil. "It is a well established law," wrote the Registrar General in 1872, "that, other things being equal, the insalubrity of a place increases with the density of the population, and that the fevers generated in crowded dwellings have a tendency to spread among the whole of the population." And it was already pretty generally recognised by Medical Officers of Health that the chief condition affecting the mortality of a locality was the density of population. The Medical Officers of Health never ceased pointing out the evils of overcrowding. "Overcrowding," wrote the Medical Officer of Health for Whitechapel in 1877, "concerns the whole community, as is strikingly shown by the spread of many diseases which are, perhaps, in the first instance endemic, and confined to these overcrowded places, but which soon become epidemic and extend over large areas, attacking, indiscriminately, all classes." And their reports are full of instances which had come under their observation. Thus, in 1871, the Medical Officer of Health for Whitechapel wrote:-- "At No. 13, Goulston Street, I found in the back room of the ground floor, closely contiguous to three closets and a dust hole, one man, six women, and three children sleeping there. The room measured 12 × 9 × 7 feet, giving only a cubic space of 756 feet for ten persons." He mentioned also "a room in Cooper's Court, occupied by man, wife, and seven children, which contained about 630 cubic feet of space, which allows only 70 feet for each." And numerous other cases of overcrowding and indecent occupation, and a case in which the dead body of a child had been retained in a room for fifteen days. Passing on to the larger aspects of this dreadful overcrowding, he wrote:-- "It is manifest that persons living in such circumstances must become so enfeebled in health as to be unfit for any employment which requires much physical strength. The mental capacity of such persons is also so low as to prevent them earning a livelihood in any occupation requiring much thought, and the consequence is an increase of paupers or of criminals, or perhaps of both." "Consumption and the whole tubercular class of disease are chiefly caused by the defective ventilation of dwelling-houses, and particularly of sleeping rooms, in which at least one-third of one's existence is passed."