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 Due to updated mapping techniques and technological advances such as GPS, bench marks are no longer maintained.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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1509 images use this description. Preview sample shown below:

SK6232 : Bench mark, Old Melton Road, Normanton by Alan Murray-Rust
SJ7719 : OS pivot mark - Aqualate Lodge building by Richard Law
SJ6511 : OS benchmark - Wellington, flats on High Street by Richard Law
SP1986 : OS benchmark - Brickhill Street Farmhouse by Richard Law
J4681 : Bench Mark, Crawfordsburn by Rossographer
NO4203 : OS benchmark & bolt - Upper Largo, Woods Hospital building by Richard Law
SK7020 : Bench mark, St Peter's Church, Saxelbye by Alan Murray-Rust
H4138 : Bench Mark 3135, Listersee Triangulation Pillar by Kenneth  Allen
SO7292 : OS benchmark - Bridgnorth, no 50 Severn Street by Richard Law
SK5439 : Bench mark, Derby Road opposite Jelley Homes by Alan Murray-Rust
NS3678 : Bench mark, Cardross Road by Lairich Rig
SE6132 : Bench mark, Old School Lofts, Millgate by Alan Murray-Rust
SK7390 : Flush bracket bench mark S 9035, The Manor House, Gringley by Alan Murray-Rust
SJ7200 : OS benchmark - Norton, South Lodge by Richard Law
SK2523 : Bench mark, 136 High Street by Alan Murray-Rust
SK7156 : Bench mark, Hockerton Road bridge by Alan Murray-Rust
SO4593 : OS benchmark - Church Stretton, Club Building in Essex Road by Richard Law
SD0985 : OS benchmark - gatepost above the cliffs by Richard Law
H4572 : Bench mark, Campsie Road, Omagh by Kenneth  Allen
SJ6507 : OS benchmark - Little Worth, roadside garage wall by Richard Law
SO6694 : OS Flush Bracket G2199 - Morville by Richard Law
SJ7008 : OS rivet - Hollinswood, bridge over Queensway by Richard Law
J3270 : Bench Mark, Belfast by Rossographer
SK7371 : Flush bracket bench market, St Nicholas's Church, Tuxford by Alan Murray-Rust
H2344 : Flush Bracket, Enniskillen by Rossographer

... and 1484 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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