AndrewK

Some more information, apparently this type of gun was called a "gingal." Other spellings include gingall and jingal. They were used in east Asia, particularly China and India, in the late 19th and early 20th centuries. It could be fired with 2 or 3 people or it could be mounted for firing by a simgle person. I highly doubt that this was issued to the soldies in the photo. It was more likely picked up while campaigning in China. There are two of these on display in the Rutherford B. Hayes Presidential Center in Fremont, Ohio.

I believe it is called a "gimble gun" or something along those lines. I can't remember exactly. I saw a couple in a US presidential museum which had an impressive artillery room. It took three men to fire one if I remember correctly. Sorry, that's all I recall.