Signal Canon ?.

[Col4570]

I have these on my Bench,I think they may be old Signal Canon.18" Barrels 1 1/2" bore.

[Col4570]

another view of one of the pair.

[Blacksmith]

The "British Ball" is a teensy bit smaller, at 1.62-inches (41.1mm).

Golf ball cannon?

Here are the safety rules before you try it out. (You know you want to)

[GhostHawk]

That looks like a whole LOAD of fun, but I would probably get in trouble.

[Ballistics in Scotland]

Ah yes, everybody should have one! They are most likely yacht-race starting guns. Merchant ships might have carried one for emergency signaling, even around 1900, but two (as used to signal a false start in a race) would be unlikely. They are almost certain to be cast iron, and probably safe to fire with black powder if the bore and touchhole suggest that they were made for use. The groove in front of the touchhole is for a powder train, permitting you the wise precaution of diving for cover. I would try it a time or two with no main charge, just to establish how long you have to do the diving. It won't be long.

The law on antique firearms doesn't actually say what an antique firearm is. But current British government policy, expressed in guidance to the police, is that they are if they were made up to 1939. It is unlikely, and very hard to prove, that they weren't. Actually firing them would require a licence, and anybody who sees someone firing a cannon these days is liable to talk long and frequently. They are under the 24in. barrel length which would be required for the relatively easy shotgun certificate, so they would have to be approved and entered on a firearm certificate. Unfortunately if they have been made as non-firing ornaments (e.g. the bore and touchhole not drilled all the way), there is no legal way of converting them into firing order.

Just observe how cannon crime has fallen off because of this.