An elaborate criticism of all the existing data regarding the volume relations of the vertical relief of the globe was made in 1894 by Professor Hermann Wagner, whose recalculations of volumes and mean heights--the best results which have yet been obtained--led to the following conclusions.[18] Areas of the crust according to Wagner. The area of the dry land was taken as 28.3% of the surface of the globe, and that of the oceans as 71.7%. The mean height deduced for the land was 2300 ft. above sea-level, the mean depth of the sea 11,500 ft. below, while the position of mean-sphere level comes out as 7500 ft. (1250 fathoms) below sea-level. From this it would appear that 43% of the earth's surface was above and 57% below the mean level. It must be noted, however, that since 1895 the soundings of Nansen in the north polar area, of the "Valdivia," "Belgica," "Gauss" and "Scotia" in the Southern Ocean, and of various surveying ships in the North and South Pacific, have proved that the mean depth of the ocean is considerably greater than had been supposed, and mean-sphere level must therefore lie deeper than the calculations of 1895 show; possibly not far from the position deduced from the freer estimate of 1888. The whole of the available data were utilized by the prince of Monaco in 1905 in the preparation of a complete bathymetrical map of the oceans on a uniform scale, which must long remain the standard work for reference on ocean depths. By the device of a hypsographic curve co-ordinating the vertical relief and the areas of the earth's surface occupied by each zone of elevation, according to the system introduced by Supan,[19] Wagner showed his results graphically. This curve with the values reduced from metres to feet is reproduced below. Wagner subdivides the earth's surface, according to elevation, into the following five regions: _Wagner's Divisions of the Earth's Crust:_ +---------------------+-----------+-------------+-------------+ | Name. |Per cent of| From | To | | | Surface. | | | +---------------------+-----------+-------------+-------------+ | Depressed area | 3 | Deepest. |-16,400 feet.| | Oceanic plateau | 54 |-16,400 feet.|- 7,400 " | | Continental slope | 9 |- 7,400 " |- 660 " | | Continental plateau | 28 |- 660 " |+ 3,000 " | | Culminating area | 6 |+ 3,300 " | Highest. | +---------------------+-----------+-------------+-------------+ [Illustration]