Géomètre au travail dans PGC 1 SPS

Geodetic measurements are often taken under an umbrella sheltering the surveyors from the sun. But an umbrella has other uses — here, a gyro-theodolite and its operator are being protected from water seeping in at the bottom of the PP1 shaft some 40 m below the surface, while preparing the survey points below ground which tell the mole where to go.