The "City" was virtually the centre of London--the centre of its wealth, its industry, its geographical extent--a precisely defined area of some 720 acres, or about one square mile in extent, and originally surrounded by walls. Its boundaries had been fixed at an early period of our history, and had never been extended or enlarged. So densely was it covered with houses at the beginning of the nineteenth century, and so fully peopled, that there was practically no room for more, either of houses or people; and from then to the middle of that century its population was stationary--being close upon 128,000 at each of those periods. Apart altogether from political influences, there were in the "City" powerful economic forces at work which profoundly affected the condition and circumstances of the people, not only of the "City," but of London. These, which were by no means so evident at one time, became more and more pronounced as time went on. All through the earlier part of the nineteenth century England was attaining to world pre-eminence by her commerce, her manufactures, and her wealth. The end of the great war with France saw her with a firm grip of all the commercial markets of the world. Her merchants pushed their trade in every quarter of the globe--her ships enjoyed almost a monopoly of the carrying trade of the world. In this progress to greatness London took the foremost part, and became the greatest port and trade emporium of the kingdom, a great manufacturing city, and the financial centre of the world's trade. It was upon this commerce that the prosperity and glory of London were built: it was by this commerce that the great bulk of the people gained their livelihood, and that a broad highway was opened to comfort, to opulence, and power. And so the commercial spirit--the spirit of acquiring and accumulating wealth--got ever greater possession of London. That spirit had long been a great motive power in London; it became more and more so as the century wore on, until almost everything was subordinated to it. That indisputable fact must constantly be borne in mind as one reviews the sanitary and social condition of the people of London at and since that time. Other constant factors there were, also exercising vast influence--the constant factors of human passions and human failings--but widespread as were their effects, they were second to the all-powerful, the all-impelling motive and unceasing desire--commercial prosperity and success. Synchronous with the rise in importance of the port of London, and with its trade and business assuming ever huger volume and variety, a noteworthy transformation took place. The "City," by the very necessities of its enormous business, became gradually more and more a city of offices and marts, of warehouses and factories, of markets and exchanges, and houses long used as residences were pulled down, and larger and loftier ones erected in their place for business purposes.