Well, from the research I have done it is the type of cannon that the British and Americans used in the late 18th century. It is 1 1/2 pounder so not a big round/ball by any means. But it was designed so a single horse could carry it, and the gun could be fired by two soldiers or in a pinch by one man. It didn't pack a big punch but had greater range than a musket or the early rifles and it still threw a nice sized ball into a mass of men.
My wife found it at an estate sale. Basically she woke up early, was first in line and said "I'll take it." Sadly the wheels had been sold at an earlier sale as this cannon had belonged to an old antique shop. The shop owners didn't know where the cannon was and sold the wheels. So we bought the gun carriage and cannon, but my wife also met the man who had bought the wheels! He didn't know what they were for when he bought them, but when he heard there was a cannon he realized they must be for that.
So we went to his place with the axle, which is about 150 pounds and determined the wheels did fit. So we came to a deal and I have all the surviving parts. Over the winter I may try to restore the gun carriage. I'm not sure if this will stay in my bunker, or if in the summer I'll put the cannon in the back yard. I'd want to stain the wood to help preserve it, and probably put some kind of clear coat to stop any further rusting from the barrel.