In the British Isles, an Ordnance Datum or OD is a vertical datum used by an ordnance survey as the basis for deriving altitudes on maps. Usually meansea level (MSL) is used. In particular: The British Isles consist of Great Britain, Ireland and a number of much smaller surrounding islands. ... It has been suggested that this article or section be merged with Datum. ... ... MAP can refer to: MAP, the ISO 639 alpha-3 for Austronesian languages Maghreb Arab Press, a news agency Malawi Against Polio Manifold absolute pressure, an important sensor in automobiles maximum a posteriori, an estimator in statistics Missouri Assessment Program Mobile Application Part, a protocol used in GSM networks Monoammonium... In statistics, mean has two related meanings: the average in ordinary English, which is more correctly called the arithmetic mean, to distinguish it from geometric mean or harmonic mean. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ...
In charge of ordnance at the Washington navy yard after 1847, he expanded the ordnance facilities and designed the 9-in.
He was commissioned in the ordnance corps and served in the Mexican War.
Crossing continents: it was founded at a time of constant invasion threats from Overseas, yet it went on to develop close links with nations around the globe.
The Ordnance Survey (OS) devised the national grid reference system, and it is heavily used in their survey data, and in maps (whether published by the Ordnance Survey or commercial map producers) based on those surveys.
The grid is based on the OSGB36 ™ datum (Ordnance Survey Great Britain 1936, based on the Airy 1830 ellipsoid), and was introduced after the retriangulation of 1936-1962.
These two datums are not really both in general use in any one place, but for a point in the English Channel halfway between Dover and Calais, the ED50 longitude lines are about 20 m east of the OSGB36 equivalents, and the ED50 latitude lines are about 150 m south of the OSGB36 ones.
Feeds |
Contact