Azure Jane Lunatic (azurelunatic) wrote,
Azure Jane Lunatic


I seem to recall a logic puzzle presented to me when I was but a chick: so a householder has a fine grandfather clock, which keeps excellent time; s/he/* sets it every year on the summer Solstice when the sun is highest in the sky. There are other, lesser, clocks in the house, not in sight of the grandfather clock. How may these clocks be kept in time?

The answer, as it was originally presented to me, was that the householder obtains a watch, synchronizes the watch with the grandfather clock, and then uses the watch to set the rest of the household clocks.

That answer always left me vaguely restless, and apparently it was sufficient for me to, many years later, have (prompted by an egregious accessibility fail that reminded me of another logic puzzle about lightbulbs) come up with a few more answers:

Answer 1 presumes that the householder is working alone. Answer 2 recruits one or more of the householder's family, housemates, or friends, who communicate the rough time to the householder while the householder is at one of the other clocks, and then an exact time mark when the master clock strikes the second. This does assume the householder (or at least one of the assistants) can hear; delays in reaction time and for sound propagation can be compensated for with preparation (shout the mark a certain amount *before* the actual mark).

Answers 1 and 2 presume that the householder must synchronize all clocks within a relatively short span of time. Answer 3 allows the householder to work alone provided the grandfather clock's chimes work, and that the householder can hear the chimes at all locations within the house. The householder waits until a short time before the grandfather clock will chime, ascertains what the time will be at the moment of chiming, and waits in readiness by each clock to be synchronized in turn. The synchronization will take several iterations that depend on the frequency of the grandfather clock's chimes before they are all complete.

Answers 1-3 presume that the other household clocks are in fact immobile. Answer 4 presumes that they are mobile. The householder fetches each lesser clock in turn, and sets them in front of the grandfather clock before returning them to their stations.

Answers 1-3 presume that the householder or assistants can hear. Answer 5 does not, and may allow for immobile lesser clocks. The householder's assistants position themselves by the lesser clocks on the summer Solstice and watch for the hour of noon themselves.

Answers 1-5 presume that anyone even cares about the lesser clocks being synchronized to within a few minutes of error. Answer 6 declares that no one does and flounces off to do something more interesting.

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