The Detroit Historical Society is still working on those details, as the layer of zebra mussels is obscuring some marks. Joel Stone, their curator, is helping with the identification and you can see his initial examination of the cannon here: http://www.detnews.com/article/20111005 ... roit-River
As for the other recovered cannons, they're also in the care of the DHS. Joel explains their history in this interview: http://www.myfoxdetroit.com/dpp/news/lo ... 0111005-mr
Great job on the part of the police divers and everyone involved!