Made by Jean and Nicholas Bouillet in Paris about 1730.
With thanks to Mike and the current owner for these pics.
Information supplied by Mike is:
"It was found in the mud on a river bank, spent 7 years in a tank of fuel oil, then restored to its present condition by a guy in England. He sold it to the present owner, then it was sent to a guy in New York State who covered the reservoir in leather. Not shootable, the parts inside are pretty thin from rust, so it isn’t able to be cocked..."