A man was talking to a noted psychiatrist at a party. "Would you mind telling me, Doctor," he asked, "how you detect whether or not an individual is mentally challenged who appears to be completely normal?"
      "Nothing is easier," he replied. "You ask them a simple question which everyone should answer with no trouble. If they hesitate, that puts you on the track."
   "What sort of question?"
   "Well, you might ask them, 'Captain Cook made three trips around the  world and died during one of them. Which one?'"

   The man thought a moment, then said with a nervous laugh, "You wouldn't happen to have another example, would you? I must confess I don't know much about history."