Geoscience Reference
In-Depth Information
Fig. 9
The southern end of Picard's and Cassini's baseline at Juvisy-sur-Orges, near Orly
Airport, is marked and commemorated by a stone obelisk, called La Pyramide, which stands
in a jumble of suburban buildings and street furniture. (Photo by the author)
the ground, its side marked by a peg. The second assistant laid his rod at the end of
the first rod, slipping a clip from the second one to the first to hold them in place
and marked his own rod with a peg. The rods were thus leap-frogged until the pegs
were exhausted and this marked out part of a baseline of ten toises length. This
pegging system made it almost impossible to lose count, and the section of ten
toises was noted down on paper. This process was repeated 500 times until the
fundamental baseline was staked out.
