There are four gravity stations in the UK, all around the Cheshire area:
Cat and Fiddle TP7177
Hatton Heath TP7237
North Rode TP7178
The outward appearance of these stations is similar to that of an FBM, except that they have a Flush Bracket on the side. There is, however, no underground chamber associated with gravity stations.
Gravity measurements are needed to determine the Geoid Model. The Geoid Model is used to convert ellipsoidal heights (usually on WGS84, ETRS89 or other GPS compliant datum) to so called orthometric heights measured relative to some determination of sea level. The ellipsoid is rarely parallel (never mind coincident!) to the equipotential surface we call sea level.
- galium_verum, Trigonomy post, https://groups.yahoo.com/neo/groups/trigonomy/conversations/messages/4976
- Rod, Trigonomy post, https://groups.yahoo.com/neo/groups/trigonomy/conversations/messages/4981
- Ian Wilson, Trigonomy post, https://groups.yahoo.com/neo/groups/trigonomy/conversations/messages/4977