This is the ancient London stone, or boundary stone, as it is alternatively called, for it has served during many ages to mark the beginning of Middlesex out of Buckinghamshire, and the termination of the city's jurisdiction over the waters of Thames. [Illustration: LONDON STONE.] The Conservancy of the river, by long prescription, confirmed by various Charters and Acts of Parliament, was vested in the Lord Mayor and Corporation. Apart from the courts, which were held by the Lord Mayor in person, and with much state, most of the administrative duties have long been performed by a committee of the Corporation, aided by four harbour-masters, an engineer, water-bailiff, and subordinate officers. Till recent times, the Navigation and Port of London Committee, as it was called, held jurisdiction from Staines in Middlesex to Gantlet in Kent, and exerted a strong hand in preventing encroachments on "the bed and soil of the river," or any injury to its banks. The duties also extended to the regulation of the moorings of vessels in the port, the deepening of channels, the erection and maintenance of public stairs, the repair of locks, weirs, and towing-paths, the control of fisheries, and the seizure of unlawful nets. Tolls and tonnage-dues contributed to the revenue on which the Corporation depended for means of executing all these obligations. They had, as one of their public advocates tersely put it, "a surplus below bridge which they were unable to appropriate, and a deficiency above bridge which they had no power of making good." Still, no hesitation or serious shortcoming appeared in their fulfilment of duties. But some years ago, a claim to "the bed and soil of the river" was set up by the Crown. Thirteen years' litigation ended in a compromise. The City consented to acknowledge the title of the Crown, and the Crown consented to grant a title to the Corporation, stipulating, however, that a Government scheme should be embodied in an Act of Parliament. Hence, the Thames Conservancy Act of 1857, which vested the rights and duties in a Board composed of the Lord Mayor, two Aldermen, four Common Councilmen, the Deputy-Master of the Trinity House, two persons chosen by the Admiralty, another person chosen by the Board of Trade, and another by the Trinity House, making twelve in all. By a later enactment these rights and duties were abrogated, and now the jurisdiction of the City over the Upper Thames has altogether ceased. [Illustration: STAINES BRIDGE.]