Aitor Alert! Manuballista found!

[P. Clodius Secundus]

The Xanten machine, on the other hand, was perhaps intended as a 2-span catapult, shooting arrows 0.40m long. It could well have been stand-mounted -- not necessarily a fixed tripod, but a portable prop in case there wasn't a handy rampart to lean it on!

Does anyone know of other evidence related to the tripods (modern generic term) used with catapultae? Particulary for iron-framed ones? My recent tests with the carroballista (see Carrus & Carroballista thread in Re-enactment & Reconstruction) have convinced me that the short braced monopods depicted on Trajan's are not just an artistic convention scaled down to fit the composition. I support this hypothesis three ways...
1. Ergonomics- We found that at "normal" height it is difficult to load and fire the weapon from the cart.
2. Physics- Shorter = stable = accurate. For taller bases the two legged "H" style is much more stable. The bed height of the carrus makes up for the difference and allows max elevation/range plunging fire.
3. Iconography- When in the carts all the frames are shown barely clearing the bed sides. Wall mounted there's no way to tell. Dismounted in the open they are shown on raised cribbing. This would give the best performance, creating a very stable platform that still allows for max range fire. If they we really normal height just "carved" shorter they'd only be useful for anti-aircraft work. :wink:
The biggest question is why do they wait until the 1C to come up with this? Was the carroballista in use before, and Trajan's just happens to be the first reference? Did did the switch to iron frames make it practical?
My results thus far would seem to indicate that weight was not the deciding factor. Was it range? If they were in-swingers with much greater range (any opinions?) that could be the key. Greater range would allow them to deploy and engage from further back in the column and give them much more time to have effect on an advancing enemy. I can cite many modern instances where a a significant advance in a weapon's capabilities leads to a major shift in it's employment.