She nodded. "After a few minutes' inspection of the berth, I found it scratched onto one of the supporting beams."
"Funny IS didn't spot it," I remarked.
"It's in our special code, silly!" Snow said. "To anyone else, it'd look like hen scratches."
"Just what is this code of yours?" I asked, curious.
Snow looked at me a moment, frowning.
"I'll carry the secret to my grave." I said generously.
She laughed, then, and said, "All right, Jery. Just a second."
From her handbag, she took out a small address book and a pencil, found a blank sheet at the back, and drew the following diagrams:
