The first comprehensive study of the currents of the Atlantic was that carried out by James Rennell (1790-1.830), and since that time Findlay in his Directories, Heinrich Berghaus, Maury and the officials of the various Hydrographic Departments have produced increasingly accurate descriptions of the currents of the whole ocean, largely from material supplied by merchant captains.
Lake Concepcion, in the Chiquitos mountains, belongs to this same hydrographic area.
This tableland, the hydrographic centre of West Africa, is most elevated in its southern parts, where heights of 5000 ft.
There are two distinct hydrographic systems in Ecuador - the streams that flow south-eastward to the Maranon, or Amazon, and those which flow westward to the Pacific. The southern Ravers.
The following table gives the approximate altitudes of the chief mountains and lakes of the continent: - The Hydrographic Systems. - From the outer margin of the African plateaus a large number of streams run to the sea with comparatively short courses, while the larger rivers flow for long 1 Estimated.
The American Crocker Land expedition, from its base at Etah, surveyed part of the coast between Etah and Hall Basin in 1914-5 and made an hydrographic survey of Foulke Fjord.
Novopashennoi for an hydrographic survey of the Arctic coast of Siberia.
He next investigated the sources of the Sutlej, made hydrographic investigations of the Manasarowar lakes, with the neighbouring underground waterways, and proceeded thence to Gartok.
The Hydrographic Department of the British Admiralty, established in 1795, undertakes the making of charts for the admiralty, and is under the charge of the hydrographer to the admiralty (see Chart).
The Sudan contains the basin of the Senegal and parts of three other hydrographic systems, namely: the Niger, draining southwards to the Atlantic; the central depression of Lake Chad; and the Nile, flowing northwards to the Mediterranean.