Hi Gene,
Thanks a lot for the link.
For a start, i would say that cannon looks most similar to mine in shape and size. Mine being in iron, only contributes for it being from the discussed period.
It also seems to have the same kind of priming hole; all such similarity pleases me a lot, for it makes me more firm on the signal cannon assumption.
Concerning the firing position, i don't know, but you can load and plug the fuse holding it partly inclined and after bring it upright, when the hole is already sealed by the burning fuse
Fernando