Inside the St. Sulpice Church, St.-Germain-des-Prés, Paris.

The inscription on the gnomon (sundial) obelisk, mutilated during the French Revolution by the supression of the names of God, the king
and of the ministers, notes that Languet de Gergy ordered this sundial from the English astronomer Sully (1680-1728) to be able to
calculate more accurately the exact moment of the equinoxes. This is in order to fix as precisely as possible the date of Easter
(though it should actually be celebrated at the full moon that follows the spring equinox!).