Curious to know if the mark was really meant for an arrow, they sculled the scow in closer to the rocks and then pulled the vines aside with one of the long boathooks.
“There are the three arrows, just as plain as day!” burst out Jack.
He was right. There, on the face of a large upright rock, the representation of three arrows had been cut. Each arrow was about two feet in length, the bottom one horizontal and the others running down to a base probably four feet long.
“It’s a triangle, all right enough! A triangle with the three angles left open!” ejaculated Randy.
“Yes, but where is the opening?” came quickly from Ira Small. He was as much excited as any of the boys.
“It must be up behind those vines!” cried Fred.
It was no easy task to get up the side of the smooth rock, and had it not been for the substantial boathooks they carried and the support of some of the vines, they would have been unable to make it. However, Jack and Randy managed finally to reach the opening and speedily began an investigation. But this amounted to nothing. The opening was very irregular, and all the passages leading from it went up instead of down.
“How are you making out?” shouted Andy, impatiently.
“Nothing doing up here, as far as I can see,” announced Jack.