January 20, 2013. 8:30 a.m. Paris time. Salon-de-Provence France. Beneath L’Ecole St. Michel.
Professor John Morse studied the notes he had made. Somehow these clues must together form a word to open the vault door. The answer, he thought, must lie in the astrolabe. Morse studied the astrolabe on the podium. The astrolabe was round, about a foot in diameter, and made entirely of brass. There were markings around the edge of the astrolabe in concentric circles. There was a small brass ring at the top about as big as a thumb. Morse held up the instrument to Father du Bois and his children, holding it by the ring. “This is an astrolabe. It is used for determining the altitude of the stars.” Morse thought of how best to explain the intricate markings and moving parts on the medieval astrolabe, and decided it would be best to use a simple analogy they could understand. He took out his notepad and drew a drinking straw, with a piece of arcing cardboard attached. He made notches on the drawing for the different degrees, and then drew in a string attached to one end of the straw, anchored at the end by a washer. His drawing looked like this: