Of the circles of the moon. I find that those circles which by night seem to surround the moon, of various sizes and redness, are caused by various qualities and thicknesses of vapours (humours) that are placed at various heights between the moon and our eyes. That larger and less red circle belongs to the first, lowest part of these vapours; the second, smaller one, is higher and appears redder, because it is seen through two vapours; and so, the higher they are, the smaller and redder they will appear, because between the eye and that circle there will be a greater mass of vapours; and by this it is proved that where the greater redness appears, there is the greater sum of vapours.

The Archimedes is complete in the keeping of the brother of the monsignor of Santa Giusta in Rome. He said he had given it to his brother who lives in Sardinia. It was formerly in the library of the Duke of Urbino; it was taken away in the time of Duke Valentino.