Update: since writing this post some 5 years ago I’ve continued to work on the problems of the pound. Related posts.
I also recommend Riggsby’s Mosaics of Knowledge (OUP 2019).
My concerns about Duncan-Jones’ potential overconfidence in his knowledge of the exact weight of the Roman pound (322.8 grams) and thus his reading of Pliny’s famous statement about 84 denarii to the pound (Money and Gov. 1994: 214-215; NC 1995: 110), led me to the publication of the above objects. It also made me very sad to have missed this conference.
Anyway, the thing about the big post-Constantinian weight above that seems striking to me is just that its weight, or more accurately its Mass. 1645 g. It’s high. And given things like corrosion we’d generally expect these things to be a little on the light side. It is clearly marked with its standard: 5 pounds. That makes 329 g to the Roman pound! See this recent discussion about the problem from a Byzantine perspective. A conservative ball park is usually 325 to 327 g for the Late Roman/Byzantine pound.
It’s a huge shame that the weight doesn’t have provenance: no mention of who current owns it and only very vague references to the eastern Mediterranean as to its find spot.
Here’s Pliny’s quote just so you have it:
In spurious coin there is an alloy of copper employed. Some, again, curtail the proper weight of our denarii, the legitimate proportion being eighty-four denarii to a pound of silver. In consequence, a method was devised of assaying the denarius: the law ordaining which was so much to the taste of the plebeians that in every quarter of the City there was a full-length statue erected in honour of Marius Gratidianus. (Pliny, Natural History 33.132)