"Whew!" he gasped, as he stopped to wipe the perspiration from his face. "If an empty sled is so hard to pull over these stones, I don't see how we are ever going to draw a loaded one."
"It's a good deal easier to draw a loaded sled on the snow-crust," said Uncle Will, encouragingly, "than it is to overcome the friction of a light weight here. To-morrow we shall be on the ice, which is even better than the crust."
"How far are we going to-day?" asked David.
"About three miles. We shall not try to go beyond the cave."
The attention of the boys was attracted by the noise of a waterfall which they could see imperfectly through the trees. The water dashed over a perpendicular cliff about one hundred feet high, and was almost enclosed by a sparkling structure of ice.
All this while the boat was in plain view, sailing on a course parallel to theirs, at a distance of half a mile. It had now outstripped them, and Uncle Will said it ought to turn in soon toward the shore. It became evident before long, however, that the craft was in trouble. She was well out from the land, but seemed to be stationary. The shore party, slowly as they moved, now steadily gained on her, and at length they could see the two occupants standing on the bow and thrusting oars or poles into the water in different places.
"She's aground!" exclaimed Uncle Will, after a moment's observation; "and the tide's going out. This is a pretty fix!"
"Can we do anything?" asked David, eager to go to the rescue.
"Oh! we might as well go on to the cave. It's not far now. We'll leave the sleds there, and then see what can be done. I don't think we can wade out to the boat yet, for there are two or three channels this side of her." So on they plodded once more.