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 Due to updated mapping techniques and technological advances such as GPS, bench marks are no longer maintained.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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3032 images use this description. Preview sample shown below:

SJ6220 : OS benchmark - Cold Hatton, Seven Stars pub by Richard Law
SP1183 : OS benchmark - Acocks Green, 338 Oulton Boulevard by Richard Law
SP1091 : OS benchmark - Gravelly Hill, Fentham Road railway bridge by Richard Law
SK5135 : Bench mark, the old school, School Lane, Chilwell by Alan Murray-Rust
SJ6705 : OS benchmark - Lightmoor, culvert below Crackshall Lane by Richard Law
SK4633 : Bench mark, Risley Lane, Breaston by Alan Murray-Rust
SK7243 : Bench mark, St. Wilfrid's Church by Alan Murray-Rust
SJ8219 : OS Flush Bracket 2454 - Cowley Cottage by Richard Law
J5080 : Bench Mark, Bangor by Rossographer
SJ8810 : OS benchmark, Horsebrook Farmhouse wall by Richard Law
C4316 : Bench Mark, Derry/Londonderry by Rossographer
SK6211 : Bench mark on Punchinello's, Melton Road by Alan Murray-Rust
SK6309 : Bench mark, St Mary,s Church, Barkby by Alan Murray-Rust
SJ9611 : OS benchmark - Shoal Hill Farm by Richard Law
SJ7010 : OS benchmark and bolt - Snedshill, St Peter's church by Richard Law
SK8803 : Bench mark, Manton Station approach by Alan Murray-Rust
TR1065 : OS flush bracket  - Whitstable, The Two Brewers pub by Richard Law
SK8538 : 1GL Bench mark with bolt, St Lawrence's Church, Sedgebrook by Alan Murray-Rust
SK7876 : Bench mark, St Peter's Church, Stokeham by Alan Murray-Rust
J5962 : Flush Bracket, Kircubbin by Rossographer
J3171 : Bench Mark, Belfast by Rossographer
SJ5813 : OS benchmark - Villa Farm by Richard Law
SP2280 : OS benchmark - Hampton in Arden, Marsh Cottage by Richard Law
SE5728 : Rivet bench mark, Lund's Tunnel by Alan Murray-Rust
SK6587 : Bench mark on the Blue Bell Inn Ranskill by Alan Murray-Rust

... and 3007 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: Tue, 14 Jun 2016

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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