Ordnance Survey Benchmark

Thursday 14 May 2020

Ordnance Survey Benchmark

Amongst all the various carvings on the stones at stonehenge from the modern graffiti of the 17th to the 20th century and the ancient axe heads and daggers from about 1700bc there are three that are not often noticed. The agencys name indicates its original military purpose see ordnance and surveying which was to map scotland in the wake of the jacobite rising of 1745there was also a more general and nationwide need in light of the potential threat of invasion during the napoleonic warssince 1 april 2015 ordnance survey has.

Ordnance Survey Art Fine Art America

Ordnance survey no longer display their benchmark values on their 11250 mapping data the values however are still available from the ordnance survey website.

Ordnance survey benchmark. The ordnance survey maps show a variety of detailed information obms being one of them. An ordnance survey benchmark in stone on the south west corner of the parish church of holy trinity at ingham norfolk england uk europe. Ordnance survey os is the national mapping agency for great britain.

An ordnance survey flush bracket triangulation points also known as trig points are marks with a precisely established horizontal position. In 2000 the ordnance survey formally announced that it was abandoning the traditional bms in favour of global positioning systems gps plus a datum conversion model. Many think it is war office related but it is in fact an os benchmark bm and a means of marking a height above sea level.

The symbol that is recorded on ordnance survey maps indicating bench marks was approved after 1854 they usually appear as an incised horizontal bar with a broad arrow immediately below the height of the bar accurately determined by spirit levelling. The bench mark database contains records of ordnance survey bench marks with particular focus on the numbered flush brackets which appear on walls and buildings across britain. Surveyors in our history made these marks to record height above ordnance datum newlyn odn mean sea level determined at newlyn in cornwall.

Ordnance survey scottish concrete obelisk including benchmark bm83006 used for surveying positioned at top of carlton hill in edinburgh scotland uk. If the exact height of one bm was known the exact height of the next could be found by measuring the difference in heights. Following the steps below you will be able to obtain specific benchmark values.

The os website says. If the exact height of one bm is known the exact height of the next can be found by measuring the difference in heights through a process of spirit levelling. These are the ordnance survey os benchmarks.

Ordnance survey and bm information is still readily available where needed and for historical comparison. Bench marks are the visible. These points may be marked by disks similar to benchmark disks but set horizontally and are also sometimes used as elevation benchmarks.

Ordnance survey bench marks bms are survey marks made by ordnance survey to record height above ordnance datum.

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