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.
"Yes; and you will note that it is at the end of what looks like a river." "But that must be a road." "It is, if this is a map, for it runs over that range of hills, or mountains." "That is plain enough." "And you will see there is a tiny, snake-like thread that winds away from that spot, which looks as if it was intended for a lake." "I see it." "That must be a river, or stream." The boys were now very excited.

All doubts were fading from their minds; the lines on the black stone had surely been intended to represent a map.
But what portion of the face of the earth did it portray?
That was a question the ring did not answer.
"Supposing it is a map," said Frank, helplessly; "what good will it do me?
I do not know what it is a map of." "But you may bet your last dollar the man in black knows." "I don't see how that is going to do me any good.
"It will do him some good, if he gets hold of this ring." "Well, I shall take care that he does not get hold of it." The map--if it were a map--on the stone served to more fully arouse the curiosity of the boys, without in any way satisfying them concerning the mystery of the ring.
Frank became so absorbed in trying to discover the true meaning of the map and in getting some light on the mystery that he began to neglect his studies.