midnight
`` Sneezing , seeing that your head will be extremely wet , is practically inevitable . But the rule applies only to such utterance as lies within human control . When the fourth vigil has been successfully accomplished , return to us for a blessing and the gray robe of our Order . '' `` But how , '' asked the King , `` during my vigils shall I know when midnight is due ? '' `` In the third quarter after eleven a bird sings . At the beginning of its song go forth from the Ring , and at the ending plunge your head into the Pond . For on these nights the bird sings ceaselessly for fifteen minutes , but stops at the very moment of midnight . ''