Guide: This civil war cannon had been fully restored and is in ready-to-

Guide: This civil war cannon had been fully restored and is in ready-to-
fire condition. But it's a good thing we're _not_ firing it
because it happens to be aimed at the main support leg of that
lookout tower. People don't realize that these cannons are very
sensitive, and the slightest jolt could set them off.
[the bus from Springfield Elementary arrives and skids into the
cannon, knocking one of its wheels off]
Of course, for safety reasons, we don't keep the cannon loaded:
it's just common sense.
-- A tour of Fort Springfield, "The PTA Disbands"