Bench Mark :: Shared Description

Bench marks were historically used to record the height above sea level of a location as surveyed against the Mean Sea Level data (taken at Clarendon Dock, Belfast, for Northern Ireland data, Newlyn in Cornwall for data in Great Britain and Portmoor Pier, Malin Head, for data relating to the Republic of Ireland). They were used as part of a greater surveying network by the UK Ordnance Survey, Ordnance Survey Northern Ireland (OSNI) and the Ordnance Survey Ireland (OSI). If the exact height of one bench mark is known then the exact height of the next can be found by measuring the difference in heights, through a process of spirit levelling. In this way hundreds of thousands of bench marks were sited all around the UK & Ireland from the mid 19th to late 20th centuries. There are several distinct types of bench mark:

- Fundamental bench marks have been constructed at selected sites where foundations can be set on stable strata such as bedrock . Each FBM consists of a buried chamber with a brass bolt set in the top of a granite pillar. See NG8825 : Dornie fundamental bench mark for an example. FBMs were used in Ireland as well as GB but those in Ireland do not have any surface markers, nor are they marked on standard maps.
- Flush brackets consist of metal plates about 90 mm wide and 175 mm long. Each bracket has a unique serial number. They are most commonly found on most Triangulation Pillars, some churches or on other important civic buildings. See J3270 : Flush Bracket, Belfast for an example.
- Cut bench marks are the commonest form of mark. They consist of a horizontal bar cut into a wall or brickwork and are found just about anywhere. A broad arrow is cut immediately below the centre of the horizontal bar. See J3372 : Bench Mark, Belfast for an example. The horizontal mark may be replaced by or contain a bolt - see J1486 : Bench Mark, Antrim.
Other marks include:
- Projecting bench marks such as SD8072 : Projecting Bracket Benchmark on St Oswald's Tower
- Bolt bench marks such as SJ1888 : OSBM bolt on Hilbre Island
- Rivet bench marks such as J3978 : Bench Mark, Holywood
- Pivot bench marks such as SJ2661 : Pivot bench mark on Leeswood Bridge

Bench marks are commonly found on older buildings or other semi-permanent features such as stone bridges or walls. Due to updated mapping techniques and technological advances such as GPS, bench marks are no longer maintained. Many are still in existence and the markers will probably remain until they are eventually destroyed by redevelopment or erosion.
by Rossographer
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1150 images use this description. Preview sample shown below:

SJ4912 : OS benchmark - Shrewsbury, United Reformed Church by Richard Law
SK7850 : Bench mark, The Poplars, Hawton by Alan Murray-Rust
SK7957 : Bench mark, Church of St Wilfrid, South Muskham by Alan Murray-Rust
SH5707 : OS benchmark - Prysgau roadside wall by Richard Law
SE6132 : Bench mark on Gowthorpe by Alan Murray-Rust
SP0288 : OS benchmark - Smethwick, Baptist Church by Richard Law
TR1066 : OS benchmark - Whitstable High Street by Richard Law
SJ8015 : OS Flush Bracket 2488 - Peartree Cottage by Richard Law
H9639 : Bench Mark, Markethill by Rossographer
J3271 : Bench Mark, Belfast by Rossographer
SJ9815 : OS benchmark(s) - House at Broadhurst Green by Richard Law
J5282 : Bench Mark, Bangor by Rossographer
D2132 : Bench Mark, Glendun Viaduct by Rossographer
SP1798 : Flush Bracket Bench Mark S8598 by Alan Murray-Rust
SP1479 : OS benchmark - Solihull, bridge south of station by Richard Law
SK5421 : Rivet bench mark, Soar bridge, Stanford by Alan Murray-Rust
SK5540 : Bench mark, 336 Ilkeston Road by Alan Murray-Rust
SJ7012 : OS benchmark -Wrockwardine Wood, Furnace Lane by Richard Law
SJ8807 : OS benchmark - Chillington, Upper Avenue gateway by Richard Law
SJ7309 : OS benchmark - Shifnal, 25 Haughtonhill by Richard Law
TG4917 : OS Flush Bracket G1460 - Hemsby by Richard Law
SK8270 : Bench mark on Highfield Cottage  by Alan Murray-Rust
SK6228 : Bench mark, Widmerpool Church by Alan Murray-Rust
J3673 : Bench Mark, Belfast by Rossographer
J3979 : Bench Mark, Holywood by Rossographer

... and 1125 more images.

These Shared Descriptions are common to multiple images. For example, you can create a generic description for an object shown in a photo, and reuse the description on all photos of the object. All descriptions are public and shared between contributors, i.e. you can reuse a description created by others, just as they can use yours.
Created: Tue, 2 Mar 2010, Updated: Wed, 8 Jun 2011

The 'Shared Description' text on this page is Copyright 2010 Rossographer, however it is specifically licensed so that contributors can reuse it on their own images without restriction.

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