His tunc primis gradibus positis ad id genus machinationis, postea cum Philippus, Amyntae filius, Byzantios oppugnaret, Polyidos Thettalos pluribus generibus et facilioribus explicavit, a quo receperunt doctrinam Diades et Charias, qui cum Alexandro militaverunt.
After these first steps had been  taken towards this kind of machine, when Philip the son of Amyntas was besieging Byzantium, Polyidus a Thessalian made a variety of designs with easier construction; his method was continued by his pupils, Diades and Charias, who accompanied Alexander on his campaigns.
final_alignments\Vitruvius_Architecture_Book_10.json