"The cunning dog has covered his tracks," said he. "He has left nothing to incriminate him. His dangerous correspondence has been destroyed or removed. This is our last chance."
It was a small tin cash-box which stood upon the writing-desk. Holmes pried it open with his chisel. Several rolls of paper were within, covered with figures and calculations, without any note to show to what they referred. The recurring words, "water pressure" and "pressure to the square inch" suggested some possible relation to a submarine. Holmes tossed them all impatiently aside. There only remained an envelope with some small newspaper slips inside it. He shook them out on the table, and at once I saw by his eager face that his hopes had been raised.
"What's this, Watson? Eh? What's this? Record of a series
