Last year I headed the engineering on a TV show where we made a catapulta in 3 days. It needed to be big for TV but also work well, so we followed the sizes laid down in Vitruvius and had advice from Alan Wilkins and Tom Feely and of course used the treatise by Marsden. It was a bit rough around the edges and some aspects could have been better, but we only managed to get off around 6 or 7 shots and in this very short time were shooting bolts 319m. It could have done considerably more. As it stands 319m is further than any other catapulta since the fall of the Roman Empire - so we were pretty pleased. Thanks to Mike Sansom for the film. The original bolts were 1.5m long and this was reduced to about 1.2m which gave the best results.