Artillery Test on Harzhorn Battlefield (235 AD)

[D B Campbell]

Meanwhile - pardon my ignorance, but what's this extraordinary-looking machine based on?

That's the large iron kamarion ("arched strut") from Orsova, designed to hold the twin kambestria ("field-frames") apart. All the wooden components are conjectural (I cannot speak for this particular reconstruction, but the components are usually based on scaling up the instructions in the Cheiroballistra text, which describes a small weapon). The size (width) of the kamarion suggests that it belonged to an "inswinger" (not as reconstructed here, which seems to have bow-arms protruding to the sides).