"I will try it to-morrow."
Until very near taps the boys talked of the mystery of the ring, and that night both of them dreamed over and over of the ring and the sinister man in black.
CHAPTER XXIX.
BART MAKES A PLEDGE.
The following day Frank obtained permission to look at the ring through the powerful microscope belonging to the academy. Bart accompanied him to the experimenting room, and they were soon taking turns in looking at the marked stone.
"What do you make of it, old man?" asked Bart.
"It looks like a map," said Frank.
"Right!" exclaimed the other lad. "It looks like a map, and I believe that is what it is."
There is a river, or road, and mountains, something that looks like a lake, and then a tiny cross. The cross must be a landmark.