“I remember your making that suggestion,” said Thorndyke; “and very much astonished I was to hear you make it. I may say that I have ascertained that Purcell was never on board that steamer—”
“Well, he might have thrown it into the sea somewhere else. There is no particular mystery about its having got into the sea. But what was there about my suggestion that astonished you so much?”
“It was,” replied Thorndyke, “that you completely overlooked a most impressive fact which was staring you in the face and shouting aloud for recognition.”
“Indeed,” said Phillip. “What fact was it that I overlooked?”
“Just consider,” replied Thorndyke, “what it was that Professor D’Arcy showed us. It was a cork button with a Terebella tube on it. Now an ordinary cork, if immersed long enough, will soak up water until it is waterlogged and then sink to the bottom. But this one was impregnated with paraffin wax. It could not get waterlogged and it could not sink. It would float forever.”
“Well?” queried Phillip.
“But it had sunk. It had been lying at the bottom of the sea for months; long enough for a Terebella to build a tube on it. Then, at last, it had broken loose, risen to the surface and drifted ashore.”
“You are taking the worm-tube as evidence,” said John Rodney, “that the button had sunk to the bottom. Is it impossible—I am no naturalist—but is it impossible that the worm could have built its tube while the button was floating about in the sea?”
“It is quite impossible,” replied Thorndyke, “in the case of this particular worm, since the tube is built up of particles of rock gathered by the worm from the sea-bottom. You will bear me out in that, Phillip?”
“Oh, certainly,” replied Phillip. “There is no doubt that the button has been at the bottom for a good many months. The question is how the deuce it can have got there, and what was holding it down.”