Ipsam machinam uti testudinem in medio habentem conlocatum in orthostatis canalem, quemadmodum in catapultis aut ballistis fieri solet, longitudine cubitorum l, altitudine cubiti, in quo constituebatur transversa sucula.
The machine itself was like the Tortoise, having, in the middle, a channel resting upon uprights (as is customary in catapults or balistas) 50 cubits long and a cubit high, on which there was placed a windlass crosswise.