:: As an
scene takes place in the Ballroom of the Palate of Tileries. The members of
the Committee for weights and measures are waiting silently. Somebody is
opening the door, Louis XVI is coming in. He is introduced to the scientists
- Monge, Meusnier, Borda, Coulomb, Vandermonde, Brisson, Tillet, Lavoisier,
Haüy, Legendre, Méchain. As he is marching past Jacques-Dominique Cassini,
director of the Paris Observatory, he stops - the two men have known each
other for a long time. "Mister Cassini, I have been told that you are to
measure a second time the meridian line of Greenwich your father and your
grandfather already did before you, do you really think you will do it
who was surprised, answered nevertheless : "Lord, I would not boast of doing
better if I had not a great advantage over them. The instruments my father
and my grandfather used only gave the measure to within about fifteen
seconds. The Chevalier of Borda here, [he points at Borda, standing amidst
his colleagues] has devised one which will give me the measure of angles
with a one-minute accuracy, this will be my credit."
scene takes place on 19 June 1791. The day after this interview, just before
midnight, Louis XVI was leaving the Tileries, heading for the kingdom East
border. Since a postmaster, Jean-Baptiste Drouet, recognized him, Louis XVI
was arrested in Varennes.
what is this so accurate instrument ? It is a very special theodolite – the
repeating circle which was invented a few years before by Jean-Charles
Borda, a physicist and sailor.
Based on La revue n° 30 (June 2000), page
56, Denis Guedj
Return of the royal family in Paris, June 25, 1791, after the escape
and the arrest in Varennes.
(Colored engraving , Paris, Musée Carnavalet - click on the
picture to increase it)