We had not long to wait. The very next train roared from the tunnel as before, but slowed in the open, and then, with a creaking of brakes, pulled up immediately beneath us. It was not four feet from the window-ledge to the roof of the carriages. Holmes softly closed the window.

“So far we are justified,” said he. “What do you think of it, Watson?”

“A masterpiece. You have never risen to a greater height.”

“I cannot agree with you there. From the moment that I conceived the idea of the body being upon the roof, which surely was not a very abstruse one, all the rest was inevitable. If it were not for the grave interests involved the affair up to this point would be insignificant. Our difficulties are still before us. But perhaps we may find something here which may help us.”