Omnes proportiones eorum organorum ratiocinatorum ex proposita sagittae longitudine, quam id organum mittere debet, eiusque nonae partis fit foraminis in capitulis magnitudo, per quae tenduntur nervi torti, qui bracchia continere ipsm tamen debent.
All the dimensions of the machines as designed are given from the proposed length of the arrow which the machine is to let fly. The ninth part of this gives the size of the opening in the frame. Through these openings twisted cords are stretched, which are to hold back the arms of the catapults themselves.
final_alignments\Vitruvius_Architecture_Book_10.json