Click on some pictures to see larger view.

This is the largest, it's bore is 1 1/8", the barrel is 16" long, wheels are 18", overall length is 28".  Built the carriage using a scrap piece of 2x4 spruce, wheels came from wagon wheel light fixtures.  Found wheels and barrel from an flea antique market.  It's very difficult to find a barrel like these.
This Cannon was built as a model with a nicely designed carriage.  The bore is1", barrel is 13" long, wheels 9", overall 25".  Purchased at a garage sale with broken axle and wheels.  A little glue and touchup and it looks great.  This has a steel barrel instead of cast iron so it's lighter.  With a full charge on a smooth driveway or sidewalk, it'll roll about a foot if you don't block the wheels.
This is the only cannon in my collection with a label (shown). It's 44 Cal, 20" barrel. 25" overall.  The label reads P Bondini Cesena 44 Cal, Black Powder only, made in Italy.  It has a very stable base and a wedge to aim barrel so it was apparently designed for target practice.  It you know anything about it, please email me.

Firing black powder cannons is dangerous and not a child's toy.  Most toy or model cannons are not meant to fire and to do so could cause serious harm.  If you have a question about your cannon, take it to a gun shop.

Each of these actually fire.  How it works:  Insert a fuse then pour black powder into the barrel.  You only need enough powder to fill up to the fuse hole, but a little more is louder.  Tamp it down well and put cotton wading in and tamp again.  Light the fuse, step back and hold you ears, it's loud enough to harm them.  Between the noise and the concussion you feel from the explosion, it's quite exciting.  I generally only fire them on the 4th of July and New Years Eve when the neighbors are more accepting of the noise, in fact they miss them when I'm celebrating the holiday out of town. 

Powder and fuses can be purchased at a local gun shop in my area.

I'll be upgrading these pictures or hopefully finding another treasure, so check back.

Cannon-Mania Antique Toy Cannons is an interesting and informative site.