But no one had seen the letter arrive; no one could tell what day or hour it had come; no one could guess how it got into the pile of the Doctor's mails; no one knew anything about it. It was one of those little post office mysteries that are always cropping up even in the best-run mail systems.
The Doctor was positively heartbroken. Often in his natural history meditations he had wondered about all sorts of different matters connected with the Ark; and he had decided that Noah, after his memorable voyage was over, must have been a great naturalist. Now had come most unexpectedly a chance to hear the great story from an eye-witness—from someone who had actually known and sailed with Noah—and just because of a silly little slip like leaving out an address the great chance was to be lost!
All attempts to trace the writer having failed, the Doctor, after two days, gave it up and went back to his regular work. This kept him so busy for the next week that he finally forgot all about the turtle and his mysterious letter.
But one night, when he was working late to catch up with the business which had multiplied during his absence, he heard a gentle tapping on the houseboat window. He left his desk and went and opened it. Instantly in popped the head of an enormous snake, with a letter in its mouth—a thick, muddy letter.
"In popped the head of an enormous snake"
"Great heavens!" cried the Doctor. "What a start you gave me! Come in, come in, and make yourself at home."