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Explanation of Types

Type Description Examples
Flush Bracket These are rectangular metal plates affixed to triangulation pillars, walls, buildings etc. If they are not affixed to a triangulation pillar they are often referred to as Non-Pillar Flush Brackets (NPFB). They are about 6" x 3" in size and the location of most of them is known through Ordnance Survey (OS) records. Each Flush Bracket (FB) has a unique serial number which makes them highly 'collectable' and there are several numbering types.  
  One to four figure number
The earliest FBs you can find and date from 1912-1921. Numbered from 1-3000. A few can be found on triangulation pillars.
Introduced in the 1920s these are found on pillars and as NPFBs. There are two sub-types, S below the number and S left of the number.
First appeared in 1936. Unlike S-series brackets numbers below 1000 do not have leading zeroes. Used extensively in Scotland and never found on triangulation pillars.
Just sixteen brackets used in London in the early 1930s.
  Five figure number
These are effectively S-series brackets above S9999 where they ran out of room for the S (S-below was discontinued as the S interfered with the measuring equipment).
Projecting Bracket An early type of metal bracket used for a short time before the introduction of flush brackets. They are all the same and have no unique attributes. Reading, Greyfriar's Church
OSBM Bolt Used alongside the G-series of flush brackets these are placed where there wasn't a convenient building or wall to provide a vertical surface on which to affix a flush bracket. They are domed metal bolts about 1" (50-60mm) in diameter fixed to horizontal surfaces engraved with OSBM and the benchmark symbol. Caban Coch Dam
Cut Bench Mark By far the most common type. Used and made from the 1800s to around 20 years ago. You won't have to walk (or drive) very far in any village, town or city in Britain before you spot one of these. Chiseled into stone, brick or wood on all sorts of vertical structures. A familiar horizontal levelling line with a three line arrow pointing towards it (usually upwards). Each one is unique depending on the mason who cut it, some are plain, some decorated. Some roughly cut, some exquisitely cut with high accuracy. Some small, some huge. Wallingford, 60 High Street
Cut Bench Mark with Bolt Old and rare these have a metal bolt screwed either alongside the horizontal cut of a cut bench mark or at the point of the cut arrowhead. Usually has what appears as a screwhead horizontal in the head of the bolt. These are highly prized by benchmarkers. Dorchester Abbey
Rivet Usually found on horizontal surfaces these are cut marks with a small metal domed brass rivet at the apex of the cut arrowhead marks. Swyncombe, Icknield Field
Pivot Fairly rare these are used on horizontal surfaces such as soft sandstone, where the insertion of a rivet would break away the stone. They consist of a small hole or depression cut to take a pivot, a steel ball bearing of 5/8" diameter (16mm). In use, the pivot is placed in the depression and the levelling staff held on top of the pivot. Sutton Bridge
Fundamental Bench Mark These are the key to the whole levelling of the UK. Granite blocks with large domed metal caps. Just like an iceberg this is just the tip of a fairly extensive underground structure. Highly accurate height stations still used today as the baseline to levelling. Conwy
Triangulation Pillar Familiar to anyone who walks in the British countryside, these can often (but not always) be found at hilltops. Most have a flush bracket affixed to one side. Huntingland


October 2005
Cut Bench MarkBerinsfield, Pumping Station
Flush BracketS0167 - Little Rollright, The Toll House
September 2005
Flush BracketG3646 - Abingdon, The Grapes
August 2005
Projecting BracketReading, Caversham Road
Cut Bench MarkDeerhurst, St Mary's Church
Flush BracketS6106 - Tewkesbury
July 2005
Flush Bracket836 - Berkhamsted
Flush Bracket834 - Berkhamsted
Flush Bracket829 - Tring Cutting - Bridge 134
Flush Bracket828 - Marsworth Top - Bridge 1
June 2005
Cut Bench MarkBegbroke, Royal Sun
Cut Bench MarkWheatley, St Mary's Church
Cut Bench MarkWheatley, Old Lock-Up
Flush BracketS6432 - Witney, Council Offices
Flush BracketS6433 - Witney, Holy Trinity Church
Cut Bench MarkPevensey, St Nicolas's Church
Flush BracketG1799 - Pevensey Bridge
May 2005
Cut Bench MarkLong Wittenham, Pumping Station
Cut Bench MarkLong Wittenham, Village Cross
Cut Bench MarkLong Wittenham, St Mary's Church
Cut Bench MarkSutton Courtenay, High Street
DestroyedS5553 - Sutton Wick
Triangulation PillarS6076 - Woolsbarrow Camp
Cut Bench MarkTyneham, St Mary's Church
April 2005
Triangulation PillarS2716 - Lyndhurst
March 2005
Flush BracketG4040 - Blewbury, Yew Tree, London Road
Flush BracketG3654 - Buscot
Flush BracketG3653 - Buscot Park, West Lodge
Flush Bracket11328 - Challow Station
Cut Bench MarkWinchester Cathedral
Triangulation PillarS1627 - Great Ormes Head
Flush BracketS0356 - Conway, Guildhall
Fundamental BenchmarkConwy FBM
February 2005
Triangulation PillarS5826 - Fore Down
Cut Bench Mark with BoltDorchester, Abbey Church
Cut Bench MarkDorchester Bridge
January 2005
Flush BracketG3632 - Watlington
Flush BracketG3635 - Benson
Cut Bench Mark with BoltBenson, St Helen's Church


All the bench marks I have logged. See my profile on the Bench Mark Database.

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Explanation of Types
Flush BracketFlush Bracket(247)
Projecting BracketProjecting Bracket(6)
OSBM BoltOSBM Bolt(16)
Cut Bench MarkCut Bench Mark(1987)
Cut Bench Mark with BoltCut Bench Mark with Bolt(134)
Fundamental BenchmarkFundamental Benchmark(8)
Triangulation PillarTriangulation Pillar(99)
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