CHAPTER XXXI—A BOLT FROM THE BLUE.

“To watch always!”

Old Joe’s words echoed in Tom’s mind. Yes, that was the law of the northland, and in some parts of it all the law that there was. Constant watchfulness was necessary to life itself in the frozen regions.

Tom’s cheeks flushed as he thought that if constant watchfulness had been observed at Camp Yukon Rover there would have been no necessity for their journey and all that it had led to.

The trail wound upward into country that grew more and more gloomy and dispiriting. There was something about the great rock masses poised above the trail, the slaty, leaden sky and the occasional gusts of wind-blown snow that struck a chill to Tom’s heart.

There was little to break the monotony of precipice and sky on the one side, while beside the trail on the other was a deep crevasse, and beyond another wall of rock. Tom peered over into the depths from time to time and thought, with a shudder, of the consequences of a fall. And that possibility was by no means remote. One slip on the treacherous foothold of the path that hung on the mountainside like an eyebrow on a face, and the victim of the accident would go sliding and plunging down the slippery slopes into that forbidding pit.

It was not a thought to inspire cheerfulness, and Tom refrained from speaking of it to his companions. But it might have been noticed that he kept to the inside of the trail. The mameluke dogs, too, by instinct avoided the outer edge and kept hugging the inside wall of the trail as far as possible from the gaping chasm.

It must have been toward mid-afternoon, as time is reckoned in those latitudes, that old Joe paused with a worried look on his face.

“Attendez!” he cried, holding up one finger.

The mamelukes stopped, their red tongues lolling out and their breath coming in long heaves. They were glad of the respite, whatever had caused it.

Tom halted behind the sled, and Jack turned his eyes on old Joe, whose face betokened the most eager attention. His body was tense with concentrated energy, as if he were putting every fiber of his being into what he was doing, which was listening.

Tom thought of the old man’s watchword, “To watch always.”

For some minutes they stood like this, and then old Joe signified that all was well and they went forward again. But ever and anon the old man cast an uneasy eye about him. It was plain that he was worried and wished the long trail were at an end.

In that gloomy canyon between the beetling walls that rose on either side seemingly straight up to the gray sky, the old trapper’s voice rang stridently as he called to his dogs or cracked his whip with loud words of encouragement.

“Courage, mes enfants!” he would cry to his struggling team. “Soon we be at Pierre La Roche’s; den plentee feesh for you—bien—Boosh! En avant!”

His words always had a magical effect on the drooping mamelukes. With stubborn determination they bent again to their task, their flagging spirits revivified by the cries of their owner.

Jack turned to Tom after one of these intervals.

“Gee whiz! but I feel like a useless log,” he exclaimed, “lolling here on a pile of soft blankets while those poor beasts are pulling me along at the expense of almost all their strength.”

“It can’t be helped,” rejoined Tom briefly. “No one supposes that you walked into that trap deliberately.”

“It’s just one of those accidents that have been happening to us right along,” rejoined Jack irritably. “We have had nothing but bad luck so far on this trip. It is too bad.”

“I agree with you,” rejoined Tom, “but, after all, whose fault is it?”

“Nobody’s, that I can see.”

“Think again.”

“What’s on your mind?”

“Just this, that it all comes from our not having forced ourselves, to use Joe’s words, ‘to watch always.’”

“Great Scott! we couldn’t have sat up all night to watch those foxes!”

“One of us could. We might have taken it in turns. However, it is too late to worry about that now. But we will have to face the music when we meet Uncle Chisholm and Mr. Chillingworth. I fancy they will have something to say on the subject.”

“Ouch! The thought of that hurts me worse than my foot,” exclaimed Jack. “I don’t much care about the idea of the explanations that will be up to us to make.”

“Yet they have to be made.”

“Er-huh,” gloomily.

“I fancy that is just the usual result of neglected duty,” responded Tom. “It is part of the price you have to pay for not being on the job.”

“Goodness, are you turning into a moralizer?”

“No. I’ve just been thinking things over. Somehow this canyon——”

Above them there was a sudden sharp crackling sound, like the trampling of a thicket full of twigs. It was followed, or rather accompanied, by a yell from old Joe.

“Back! Get back!”

The next instant Tom echoed his cry.

Simultaneously old Joe sprang forward and tried to turn the mamelukes, but they, maddened by fright, plunged forward.

From above, loosened from its foundation by the softened snow, a huge rock was bounding down upon them. Had the mamelukes stopped where they were they might have been saved. As it was, their plunge forward had brought them directly in the path of the great boulder. The destruction of the sled appeared certain.

And on the sled was Jack, crippled and unable to make a move to save himself from the impending doom.