J3474 : Bench Mark, Belfast

near to Shankill, Belfast County Borough, Ballymacarret, Skegoneill and Cliftonville, Ireland

Bench Mark, Belfast
Bench Mark, Belfast
A bolt bench mark set into the northern side of the Commercial Buildings, Waring Street, Belfast. See J3374 : The Commercial Buildings, Belfast (detail) (4) - the mark is just visible on the extreme bottom right of picture, partially obscured by the railings. This mark dates from the 1st levelling of Ireland which took place in 1839-43 and is probably the last mark from that period still extant in central Belfast.
The original remarks for the mark describe it as
"Copper bolt driven vertically into stone in North front of Commercial Buildings, Belfast; 1.3 feet above centre of road". It was initially levelled to 20.226 feet above sea level.
Today the mark has been levelled to 3.11 metres above MSL.
This mark was the principle starting point for levelling lines leading from and to Belfast. From here lines of levelling went south to Armagh, east to Newtownards & Donaghadee, north to Antrim & onto Coleraine and north-east to Carrickfergus and on up the coast road to Portrush.
See also LinkExternal link for many other examples I have found.
Bench Mark
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.
Creative Commons Licence [Some Rights Reserved]   © Copyright Rossographer and licensed for reuse under this Creative Commons Licence.
year taken
2010
· Find out how to reuse this image · For example on your webpage, blog, a forum, or Wikipedia. ·
Discuss There are 4 posts in a discussion
on J3474
(preview on the left)
Modify Suggest an update to this image Email Contact the contributor
Loading map... (JavaScript required)
Grid Square
J3474, 2714 images   (more nearby)
Photographer
  (find more nearby)
Image classification?
Supplemental image
Date Taken
Thursday, 8 July, 2010   (more nearby)
Submitted
Friday, 9 July, 2010
Category
Bench Mark   (more nearby)
Subject Location
Irish: geotagged! J 340 744 [100m precision]
WGS84: 54:36.0519N 5:55.6264W
Photographer Location
Irish: geotagged! J 340 744
View Direction
South-southeast (about 157 degrees)
Clickable map
+

This page has been viewed about 58 times.
View this location: KML (Google Earth) · Google MapsExternal link · Geograph Map · geotagged! More Links for this image
NW N NE
W Go E
SW S SE
[Mark
You are not logged in login | register
please donate