Before the appearance of the ballista and other similar machines, the power of a weapon was limited to the frame of itself. Around 350 BC, the technology of a torsion powered machine was born (Nossov 136) Torsion machines uses ropes or animal cords tightly wound with a wooden arm in the middle to fire projectiles. By twisting the rope, these people were able to achieve greater power from their weapons and it was less likely to break their machines, just the ropes.
Although the original appearance of ballistae was around 350 BC, it wasn’t until roughly 334 BC that they started being widely used. Alexander was the first to start using these machines, which fired large arrows usually to take out soldiers, not structures (Nossov 136). As time progressed, they were adapted to throw stones. This meant the ballista was equipped with a larger frame and also metal parts began to be integrated into the construction to support the strain (Wikipedia 2012). With the capability of throwing stones, they were now able to take out structures rather than mainly soldiers. There is a wide variety of the calibers of stones used, each having its own purpose. The stones which were thrown ranged from 10 pounds up to 85 pounds; with the lighter stones being used primarily for defense and the heavier stones being used for offense (Nossov 138).
The ballista was a fairly simple weapon for the average soldier to operate; it worked similarly to a crossbow. Soldiers pulled levers at the rear of the machine to retract the pusher through a series of ratchets. All the energy was stored in the ropes, which carried a much higher potential energy than could have possibly been stored in
the wooden throwing arms. Due to this ratcheting system, it could be ready to fire in a moments notice. This weapon was highly accurate and there have been multiple accounts of skilled ballista shooters being able to take out enemy soldiers from a few hundred yards (Wikipedia 2012). Although they were highly accurate, they
weren’t able to shoot very large projectiles and this eventually became the job of newly developed catapults (Nossov 150).
In this early version of a ballista, it can still be seen how they were used to fire arrows. These machines were relatively small, but that made it much easier to carry from place to place. As these weapons grew with new engineering techniques, they became more complex and had to be built more durably. As a result, metal was added to these machines, but this also made transportation more difficult. This required that they needed to be disassembled and reassembled at the site of war.
E. Schramm: Die antiken Geschütze der Saalburg. (Berlin 1918), S. 41 Abb. 14, 42 Abb. 15
Gurstelle, W. (2001). Backyard ballistics. (pp. 91-101). Chicago: Chicago Review Press.
Gurstelle, W. (2004). The art of the catapult. (pp. 60-69). Chicago: Chicago Review Press.
Nossov, K. (2005). Ancient and medieval siege weapons. (p. 136, 138, 150). Guilford: The Lyons Press.
Rockwell, P. (Photographer). (1999). Carroballistae. [Print Photo]. Retrieved from http://www.stoa.org/trajan/buildtrajanpage.cgi?21
Wikipedia. (2012, April 08). Ballista. Retrieved from http://en.wikipedia.org/wiki/Ballista