This picture shows a so-called "Cheiroballista" being used by ancient romans.
The Cheiroballista was a ancient version of a crossbow, invented around 100 BC and was used in many battles. The word Cheiro- or Manuballista would be translated as Handballista, because it was one of the most effective seige-weapons the romans had which could be carried and used by a single person.Rope springs were set in the frame angled to each other in the form of a "V", which increased the power. A very sturdy frame accommodated the extra torque, which meant extra weight, and less maneuverability. The rope used in it was made of animal-, and human- hair, and also of animal tendans.
-An amazing invention which is almost genius to me...
