In some places, moreover, ground was entirely cleared of houses for the construction of docks, or for the erection of great railway termini. How marked were the effects of these changes is evidenced by the fact that from 17,190 inhabited houses in the "City" in 1801, the number had sunk to 14,575 in 1851. The explanation was the simple economic one, that land in the "City" yielded a much larger income when let for business than for residential purposes. Offices and warehouses were absolutely essential in the "City" for business. What did it matter if people had to look for a residence in some other place? London was large. They could easily find room. And the process, without control of any sort or kind, and wholly unimpeded by legislation or governmental regulation, went on quite naturally--entailing though it did consequences of the very gravest character, then quite unthought of, or, if thought of, ignored or regarded as immaterial. This then was, at that time, and still is, one of the great, if not indeed the greatest of the economic forces at work which has unceasingly dominated the housing of the people not only in the "City," but in the metropolis outside and surrounding the "City," and, in dominating their housing, powerfully affected also their sanitary and social condition. The "City" was in the enjoyment of a powerful local governing body--namely, the Lord Mayor and Corporation, or Common Council, elected annually by the ratepayers; and numerous Acts of Parliament and Royal Charters had conferred sundry municipal powers upon them. For that important branch of civic requirements--the regulation of the thoroughfares and the construction of houses and buildings--they had certain powers. The vastly more important sphere of civic welfare--namely, the matters affecting the sanitary condition of the inhabitants--was delegated by the Corporation to a body called the Commissioners of Sewers, annually elected by the Common Council out of their own body, some ninety in number. And these Commissioners had, in effect, authority in the City, directly or indirectly, over nearly every one of the physical conditions which were likely to affect the health or comfort of its inhabitants. They could also appoint a Medical Officer of Health to inform and advise them upon public health matters, and Inspectors to enforce the laws and regulations. The "City" was thus in happy possession of a powerful local authority, and a large system of local government. And it stood in stately isolated grandeur, proud of, and satisfied with, its dignity, and privileges, and wealth; glorying in its own importance and splendour; content with its own system of government, and its powers for administering its municipal affairs, and indifferent to the existence of the greater London which had grown up around it, and which was ever becoming greater. Greater indeed. The population of the "City" in 1851 was 128,000; that of the metropolis not far short of 2,500,000.