Betty was about to reply, when, with a sharp report, a large piece broke off their cake of ice. This left one of the runners on the forward cross-piece close to the lapping water. "Oh dear!" cried Amy. "If this keeps up----" "Isn't that a man over there?" suddenly cried Betty, pointing toward shore. "Yes, girls, it is. A man! Oh, shout to him! Call for help!" The next instant there went echoing over the expanse of ice-strewn water four young voices, uniting in a call for aid. Fortunately the wind was right, and the man heard. He had been walking along the river shore, and now, looking up and across, he saw the girls in the ice boat in their perilous position. It needed but an instant for him to sense the situation, and he acted promptly. He waved his hand as a sign of encouragement, and his voice came faintly to the girls, but they could not make out what he said. The man ran back up the shore a little way. "Where's he going?" asked Amy. "Oh, he's going to leave us!" "No, he's probably gone for help!" said Betty. "Oh, there goes another piece of our floe!" "Help! Help! Hurry!" shouted Mollie, the others joining their voices to hers. Presently the man was seen to be pushing something down to the river. "It's a boat!" cried Betty. "Now we're all right!" And it did seem to be some sort of boat in which the man was coming to the rescue. CHAPTER XXI A HELPING HAND "What is he doing?" "What a queer boat!" "Sometimes it's in the water, and again it's on the ice!" "No matter! He's coming to save us, and it's high time! There goes another chunk off our ice raft!" It was Betty who gave voice to the last, and Grace, Amy and Mollie in turn, who had expressed the other sentiments. All were true in their way. The man did certainly seem to be advancing in a peculiar manner. At times he appeared to be rowing, or padding, and again he propelled himself over a big cake of ice, pushing himself along by means of short poles on either side of the boat. And, as Mollie had said, at times he was in the water, and again gliding over the ice. What Betty had said was but too true. Now and then, with a startling report, the big floe on which rested the auto ice boat containing the girls would be lessened by a great chunk, that would break off, and go floating away. "Oh, hurry! Do, please, hurry!" breathed Grace, as she sat huddled close beside Amy, gazing now and then into the ice-encumbered black water that seemed momentarily to be encroaching on their margin of safety. "We can never all get in that boat!" decided Amy, as the man alternately pushed and paddled it toward them. "It will only hold two, and he'll have to make four trips. It may be too late--for the last one!"