A watchman's stopped watch is the only clue to when a crime happened
After a robbery at a riverside wharf, the only clue to the time of the crime is the night watchman's watch, stopped during the struggle. Before anyone thought to check it carefully, an officer had already fiddled with the hands trying to restart it. All he can now recall is that when it stopped, the hour and minute hands pointed in exactly the same direction, and the second hand had just ticked past the 49th second. Assuming the watch kept perfect time, what time did it actually stop?
Reveal the answer
4 hours, 21 minutes and roughly 49.9 seconds past twelve. The hour and minute hands line up exactly only 11 times every 12 hours, about every 65 minutes 27 seconds, and only one of those moments has the second hand just past 49 seconds. Dudeney published this in Amusements in Mathematics (1917), as a dig at a novelist who'd gotten a similar clock scene's arithmetic wrong.
— Henry Ernest Dudeney, Amusements in Mathematics — Thomas Nelson & Sons, 1917
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