But they soon fell asleep; and most of the next day they were out tobogganing with the other children, and they soon became so good at it that they could go as fast as any of them, and hardly ever had a spill. By the end of the week they had got into the habit of climbing on to the top of Cape Fury and tobogganing back again, more than a mile and a half, right down to Mr Smith's house. The first time they climbed up there the slope had looked so steep, and the roofs of the houses so far below them, that they had stood for nearly ten minutes before they could make up their minds to start. But some of the other children had done it, and at last Doris had said, "Well, come on, Cuthbert, we mustn't be afraid," and Cuthbert had told her to hold on tight, and so they had pushed off over the frozen snow.
By the time they had got half-way, they were going so fast that the air was roaring in their ears, but the track was straight, and they had kept in the middle of it, and ran safely into the town. After that it didn't seem worth while to go tobogganing on any of the lower hills, and that was how it came about that the following Wednesday they found themselves as usual on the top of Cape Fury.
It was a still, cold day, and the air was so clear that they could see the coast for miles and miles, and the tops of mountains far inland that they had never seen before. Below them in the bay, stuck in the ice, they could see the little steamer, with the sailors on the deck, and beyond the ice a strip of blue water, and beyond that again more ice still. That was on one side of them, and on the other they saw the farther slope of Cape Fury, slanting down and down and down to the unexplored regions toward the north. It was a gentler slope than the slope toward the town, and suddenly Cuthbert had a great idea.
"I say," he said, "why shouldn't we toboggan down there? I don't suppose anybody has ever done it."
What with the wind and the sun and the snow, the cheeks of both of them were like ripe chestnuts, and Doris's eyes began to sparkle as she listened to Cuthbert's great idea. When he was at home Cuthbert didn't get many ideas, and he generally used to laugh at other people's, so he was very pleased when he got this one and Doris said that she thought it ripping.
"We won't go too fast," he said, "so that, if we see a precipice or anything, we shall be able to stop ourselves in time."
They had a stout little toboggan, just big enough for two, and so they started off down this new slope, with the sun shining and the snow glittering. At first they moved quite slowly, but lower down the side of the hill became steeper, and soon they were going so fast that, even if they had wanted to, they would have found it pretty hard to stop themselves. And then an awful thing happened, for suddenly, just in front of them, they saw a deep cleft in the snow sliding down, at a terrific angle, into a sort of tunnel under the hillside.
Almost before they could breathe, they had plunged into this, and now there was nothing to do but to hold on. They saw the tunnel's mouth leaping toward them, and the next moment they were in darkness. Neither Cuthbert nor Doris had ever been so frightened before. In the pitchy blackness they could see nothing. They could only feel themselves shooting deeper and deeper into the very heart of the frozen earth. Sometimes a bump on the floor of the tunnel would send them careering toward the roof, and then they would come down again with a thud that almost pitched them off the toboggan. Every moment they expected to be killed. There came another tremendous bump. And then they felt their toboggan springing through the air and dropping like a stone into some fearful well. They shut their eyes, waiting for death, and then went rolling over and over, with something strange and soft and feathery wrapping them round like a bedroom quilt. For a minute or two they could only gasp, and then Cuthbert sat up and called to Doris.
"Hullo, Doris!" he said; "are you all right?"
"Yes, I think so," said Doris. "Are you?"