The code, enciphered in the French language (despite its introduction), decoded to "Michel Florencio van Langren says that one should make two cylindrical copper vessels of equal volume that have a conical end at the bottom, in which a hole is made in the middle so that when they are filled with seawater, they let a line of water run until they empty. The stars know in how much time they must be empty. This noted, the first barrel is run on departure, while recording which known star is on the meridian. This vessel will be empty when this star is back on the same Earth meridian, knowing that it is empty in 24 hours of sidereal time. At the same time as when the first vessel stops flowing, the second vessel opens, which will also be empty when the said star is back on the meridian of departure. This careful operation will be done daily during the trip mentioned here if one wishes to know how many degrees of longitude one has traveled from the meridian of departure. One has only to determine this difference from the stars in the sky each time one of the vessels is empty. Not to be surprised, a cylindrical float floating on cork is used to indicate".