Page "Cannon" Paragraph 12

* Vent: A thin tube on the near end of the cannon connecting the explosive charge inside with an ignition source outside and often filled with a length of fuse ; always located near the breech.

Sometimes called the fuse hole or the touch hole.

On the top of the vent on the outside of the cannon is a flat circular space called the vent field where the charge is lit.

If the cannon is bronze, it will often have a vent piece made of copper screwed into the length of the vent.