You may try rubbing the surfaces with a little white chalk dust then wipe it off. It should leave the dust in the letters and make reading the sundial a lot easier. Try taking a photo of the reverse side to see if the location names appear more clear with chalk dust in the letters.
For instance, Montreat 45 is in fact Montreal 45 degrees north. S fa Fes is probably Sta Fe or Santa Fe 31 degrees north. Santa Fe is at 35.5 deg N. The margin of error is acceptable as the early maps of New France were badly in error. The place names on the reverse side are most likely all New World locations in old French, Indian, English and Spanish.