Wouldn't this be a hoot to develop cast loads for? Obsolete almost as soon as it reached the naval vessels, this is a big brute - bore size 1.475 inches! The size is hard to gage in these photos but I was looking up at it. The pistol grip gives some impression. One wonders if there are many of these in private collections or if there are many people alive who have shot one.
The brass plates on top read, "VICKERS SONS & MAXIM L No 2250 37m/m AUT. GUN MARK II" and give patent dates from 1889 to 1895. I will have to research the specs for the ammo and would love to see a picture of the cartridge/shell.
This example resides in Farragut Park in Bridgton Maine. You don't run into these odd ducks often.