TO THE READER.

Yet Bullialdus, unmindful of his promise, deemed it sufficient to insert into his Prolegomena only a very few documents from this work of Theon—which is most useful for the history of astronomy—and these were not the best selected. Menagius Gilles Ménage, French scholar and writer also, either through Vossius or from the codex of the Archbishop of Toulouse, had known of something existing from Eudemus' History of Astronomy within Theon of Smyrna's Astronomy. But neither Bullialdus, nor Menagius, nor anyone else to this day has published this astronomical part of Theon's work, although J. A. Fabricius had hoped it would happen soon.

Fabricius himself, in his notes to the first ten verses of Alexander which he publishes after Gale, writes: "The Greek verses of Alexander were preserved for us by Theon of Smyrna, in his book On Those Things in Mathematics Useful [for the Reading of Plato], in that part which covers astronomy, and which survives in manuscript at Paris in the Coislinian Library and at Milan in the Ambrosian Library." But it is false that Theon's Astronomy was among the codices of the Coislinian Library. Indeed, the codex of his work at Milan