There is a plaque under the cannon accessible with the green car, saying "The Cannon Monument – This cannon was put here by
Operating the cannon Edit
The cannon is fired with a big red button on the panel.
It can also be lifted from the ground and moved left or right. In order to enable moving controls, two codes consisting of three symbols must be entered. The first one (for moving up/down) can be found in the small basement room in Hall of Records, and the other (left/right) is displayed in the purple guy's cavern. After entering the correct symbols, two axes appear on the target viewer and by clicking the arrows the cannon is moved. It's impossible to move it right unless lifted from the ground, yet Klogg can do it using his remote control when he shoots Bil (and later himself).
Klaymen must use the cannon to:the Clockwork Beast, Klogg protects himself from the intruders by shooting Bil in his chest. At Good Ending, Klogg accidentally steps on the remote control and shoots himself off the Neverhood.