Who Watches the Watchman?

Christopher Fahey on the Detex Newman watchclock, a clever hundred-year old mechanical system that solves the following problem:

Let’s say you own a big building full of valuable stuff. How do you make sure that the night watchman patrolling your factory floor or museum galleries after closing time actually makes his rounds? How do you know he’s inspecting every hallway, floor, and stairwell in the facility? How do you know he (or she) is not just spending every night sleeping at his desk?

★ Monday, 4 May 2009