"That is what it is. I should not have noticed the wood if the peculiar lettering had not shown up through the coating."
"What are the letters, and do you know what they stand for?"
"We had better not pass judgment on that until we have removed all the calcium."
At this moment Harry came in to view the slab. It was the slab he had carelessly picked up in the cave, and therefore it had a great fascination for him. The calcium was carefully chipped off, and it was found to be a piece of oak board, with a smooth cut-off end, parallel sides, nine inches wide, nearly two inches thick, and about eleven inches long, the opposite end having the appearance of being broken. The only letters which could be made out were "HI," and a portion of another letter which could not be determined.
Fig. 14. The Slab Found in the Cave
"What do you think the letters were intended to indicate?"