The brass plate used as a mounting point for a theodolite on top of a concrete British Ordnance Survey triangulation point, or Trig Point
Schlüsselwörter
triangulation,
point,
trig,
ordnance,
survey,
bench,
mark,
elevation,
coordinate,
britain,
british,
reference,
number,
map,
measurement,
metal,
plate,
surveying,
pillar
Deutsch
