Newlyn Tidal Observatory
... that the mean sea level observed by the Newlyn Tidal Observatory from 1915 to 1921 defined the reference for height measurement in Great Britain?
... that the <a href="./Sea_level" id="mwAZk" rel="mw:WikiLink" title="Sea level">mean sea level</a> observed by the <b id="mwAZo"><a href="./Newlyn_Tidal_Observatory" id="mwAZs" rel="mw:WikiLink" title="Newlyn Tidal Observatory">Newlyn Tidal Observatory</a></b> from 1915 to 1921 defined the <a href="./Vertical_datum" id="mwAZw" rel="mw:WikiLink" title="Vertical datum">reference</a> for height measurement in Great Britain?