Perhaps he had understood.

She could not tell, but her quick eye had caught sight of a long, thin plank on the shore.
Pulling off one of her mittens, she showed him a little pearl and turquoise ring her mother had given her for a birthday present, indicating that she would give it to him if he would help her.

Then she seized one end of the plank and made a sign for him to take the other; but the stubborn creature began to unload the chips from the wagon.
Grace ran blindly ahead, dragging the plank alone.
"He's feeble-minded," she quivered.

"I suppose I shall have to work this thing by myself." When she had reached the bank, Grace heard him trotting behind her with his little wagon.

In another moment there was a tug at the board.