Ordnance Survey Benchmark (OSBM) used for levelling height above Ordnance Datum (OD).
Height (1954): 10.7675m OD (Newlyn). Mark verified by the Ordnance Survey in 1954. Description: FL BR SO558 TH NE ANG E FACE. 0.5m above ground. 1st Order BM.
The bracket was used on the Aberaeron to Carmarthen secondary line of the Second Geodetic Levelling of England & Wales in 1927-1928. It was levelled with a height of 35.556' above OD (Newlyn). Description: NE angle of Town Hall, Cardigan. Abstract A 471:
Link [OS 54/136].
The bracket was used on the Aberayron to Carmarthen secondary line of the Second Geodetic Levelling of England & Wales in 1953-1954. It was levelled with a height of 35.393' above OD (Newlyn). Abstract S 7:
Link [OS 54/639].
The bracket was used on the Haverford West to Cardigan line (G077) of the Third Geodetic Levelling of England & Wales in 1954. Abstract G 65:
Link [OS 54/754]
Context:
SN1746 : OSBM Flush Bracket S0558 - Cardigan Town Hall