Onager - range/size/load

[Nathan Ross]

Larger onager over 300 metres

Thanks again! I see that in his comments on the siege tower of Demetrius Poliorcetes, Vitruvius writes that it was intended to 'withstand the blow of a stone weighing three hundred and sixty pounds shot from a ballista' - this implies that 360lbs was the maximum weight of shot. Is Vitruvius generally held to be reliable in his measurements?

If so, and if we could assume that the largest sort of single-armed onager could throw a missile of the same weight as the largest sort of twin-armed ballista (and if not, why switch to an inferior weapon?), then it does seem that this sort of weight of shot would be feasible - and perhaps over 300 metres too.

Would a single-armed onager allow a higher trajectory shot from its sling than a stone-throwing ballista, perhaps? If so, then we could be looking at an even greater range.