TO THE READER.

Dec. 19, 1922 EM,

Recd. 9-20-35. NP 7.

Having been long occupied with the history of the physical sciences among the ancients, and while I was entirely focused on writing the second volume, which is to be dedicated to ancient astronomy, I felt a serious lack. The astronomical portion of the work of Theon of Smyrna, the Platonist philosopher, titled On Those Things in Mathematics Useful for the Reading of Plato, has not yet been published in print and was neglected by those who have written the history of that science. The manuscript of this work was seen in Milan at the Ambrosian Library by Isaac Vossius, and, as attested by Bullialdus Ismael Bullialdus, an astronomer and mathematician, "he had observed many excellent things in it, as much as the customs of that region had permitted him."

Writing the history of astronomy, Bailly Jean Sylvain Bailly, 18th-century astronomer and politician, after speaking of that Milanese manuscript of Theon's Astronomy...

¹ In the edition of the arithmetic part of Theon of Smyrna’s work, To the Reader, p. 9. Paris, 1644, in-4°.
² History of Modern Astronomy, Clarifications, book II, § 44, vol. I, p. 504.

A rectangular library stamp at the bottom center of the page contains the number 641041.