TO THE READER.

actually fit the text, and illustrated with a dissertation and notes—a passage from Chalcidius. This passage, wrongfully neglected by those writing the history of astronomical science, appears to have been drawn from some lost work, either by Theon himself or by Adrastus, whom Theon is accustomed to follow as an authority in astronomy.

The following Dissertation will show you that I have omitted nothing that I could apply toward the most diligent preparation of this edition of Theon of Smyrna’s Astronomy.

I wrote this at Rennes, having completely prepared the edition, which is now being requested by me to be printed by the royal press.

September, 1847.