It was a small tin cashbox 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 of messages in the advertisements of a paper. Daily Telegraph agony column by the print and paper. Right-hand top corner of a page. No dates⁠—but messages arrange themselves. This must be the first: