Finally, a goblin squad showed up to test my Clockwork Drowning Chamber.
-You will see that this drowning chamber closes, fills, waits, and empties without a single "Pull the Lever!!" command. Some gobbos run through the chamber quickly. Some gobbos drown and gets sucked down into the drainage system. Two gobbos manage to hold their breath long enough to escape.
-The principle is sound, but obviously it needs to work. Check out "Waterguards 163 Late Winter" for all the detail.