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 Due to updated mapping techniques and technological advances such as GPS, bench marks are no longer maintained.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
Related descriptions Selection is automatic and approximate, it might not always select closely matching descriptions

1566 images use this description. Preview sample shown below:

SP1289 : OS benchmark - Hodgehill, 93 Twycross Grove by Richard Law
H8583 : Flush Bracket, Moneymore by Rossographer
SO4382 : OS benchmark - Craven Arms, Corvedale Road by Richard Law
SK6730 : Bench mark, former Methodist Chapel, Kinoulton by Alan Murray-Rust
SJ7907 : OS flush bracket 10562 - Tong former Post Office by Richard Law
SJ8909 : OS benchmark, Somerford bridge by Richard Law
SO7193 : OS benchmark - Bridgnorth, Listley St by Richard Law
SD9205 : Bench mark on Church of St Mary and St Peter by Alan Murray-Rust
SO7192 : OS benchmark - Bridgnorth, Castle Hill Walk by Richard Law
SD7109 : Bench mark, Bradshawgate by Alan Murray-Rust
J3372 : Bench Mark, Belfast by Rossographer
J3474 : Flush Bracket, Belfast by Rossographer
SO7193 : OS Flush Bracket S6051 - Bridgnorth High Town by Richard Law
J4874 : Bench Mark, Newtownards by Rossographer
SO4693 : OS Flush Bracket 2876 - Hazler Coppice by Richard Law
SK8704 : Flush bracket bench mark S9813, Horse and Jockey, Manton by Alan Murray-Rust
SJ7702 : OS benchmark - Ryton, Caynton Cottages by Richard Law
SP1679 : OS benchmark - Solihull, electricity building by Richard Law
SJ7008 : OS benchmark - Hollinswood, rear of 19 Dunsheath by Richard Law
SK5637 : Corner of the tower, St Wilfrid's Church by Alan Murray-Rust
SK5336 : Bench mark, Nether Street School by Alan Murray-Rust
SK5739 : Bench mark on Nottingham Station by Alan Murray-Rust
SJ5501 : OS benchmark - Evenwood Farm by Richard Law
H2344 : Flush Bracket, Enniskillen by Rossographer
SE7871 : Location of bench mark, Wheelgate, Malton by Pauline E

... and 1541 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.

You are not logged in login | register
Get Involved