On the floor of the western end is the meridian traced by the astronomer Cassini while engaged in the triangulation of France.
"The South of France--East Half"
Charles Bertram Black
It is commenced by a primary triangulation, and principal and verification bases; it is carried on to a second triangulation, with very accurate instruments, so as to determine 'all the principal points; the filling up the interior is completed by a peculiar species of plane table; and in order to do away with the inaccuracies of the common chain, the triangulation is carried down on paper to the most minute corners of fields.
"Thomas Davis, Selections from his Prose and Poetry"
Thomas Davis Commentator: T. W. Rolleston
The altitude had been measured by triangulation by the hydrographer of the expedition, but I had other methods of measuring the ascent.
"My Attainment of the Pole"
Frederick A. Cook