The scale finally adopted of 1/2500, on which the whole of England has at last been surveyed, is one which corresponds with that adopted for the national maps and plans of the chief countries for Europe. Lastly it possessed the incidental advantage that a square acre is to all practical intents represented on the plans by a square inch. Among the many public purposes which the national map was expected to subserve are the following: the valuation of property for the equitable adjustment of taxation and assessment; the sale and transfer of land and the registration of title; railway and other civil engineering work, such as the construction of roads and canals, large sanitary and drainage schemes, military engineering works, hydrographical, geological and mineral surveys; the reclamation and improvement of waste lands, and of land from the sea; transactions affecting land as between landlord and tenant; statistical surveys, the setting out and adjustment of parochial and other public boundaries and so forth. It has been amply proved on the best evidence that a map, with levels, on a scale of something like twenty-five inches to one mile is the smallest which can properly fulfill all these requirements. In the organization and equipment of the Ordnance Survey, as it exists to-day, no pains are spared to secure the utmost precision and economy in its methods of field work and publication. After more than a century of development and the completion of the cadastral map, let it not be supposed that its mission is at an end, for it is proposed to make a complete revision of all the cadastral work at least once every twenty years. This is rendered necessary by the constant changes in property boundaries, and the growth of population--which may be gathered from the fact that the city of London increases in population at the rate of about 50,000 a year, and that eighty or more miles of new streets are added in the same time. II. The Ordnance Survey of Great Britain as it exists to-day is a remarkable Publishing Bureau, from whose presses are given the most elaborate and accurate series of maps which any country possesses. Maps not alone confined to the representation of the physical features of the country, but containing every detail of interest or value for civil or military purposes. It has justly gained the commendation of the French that it is "a work without precedent, and should be taken as a model by all civilized nations." The principal scales of publication adopted by the Ordnance Survey are: (1) A general map on the scale of one mile to one inch. (2) County plans on the scale of six inches to one mile. (3) Cadastral or Parish plans for the whole country on the scale of 1/2500 or about 25-1/3 inches to one mile, on which one square inch on the plan represents an area of one acre. (4) For towns of over 4000 inhabitants a scale of 1/500 of actual length on the ground or 10-56/100 feet to one mile.