They found the mouth of the mammoth cave, near which lay all that was mortal of poor old Magnus and his son, after days and days of digging; but when at long last they succeeded in forcing an entrance, one glance around them proved that they had indeed fallen upon riches and wealth untold. Those vast tusks and teeth of the mighty monsters of an age long past and gone were of the purest ivory, more white and hard than any they had ever seen before.

“Why, sure,” said Rory, “the cave of Aladdin was nothing to this!”

“The next thing, gentlemen,” said the captain, “is to transport our treasure to the good ship Arrandoon. Seth, old friend, your dogs will be wanted now in good earnest.”

“I reckon,” replied Seth, “they’re all ready, sir, and just mad enough to eat each other’s collars, ’cause they don’t get anything to do.”

What a change it was to have sunshine and a comparative degree of warmth again. Rough and toilsome enough was the road between the ship and the mammoth cave, but the snow was crisp and hard. The dogs were wild with delight, and so were our heroes, and so hard did everybody work all day that no one thought any more about the diving-bell and the denizens of the deep. After dinner they needed rest. Rory took his boat, or canoe, with him once or twice, and, all alone, he embarked on the volcanic lake and paddled round the geyser.

In three weeks from the day they had found the entrance to the cave they had transported all the ivory to the Arrandoon. They were now what Silas would have called a “bumper ship.” If they should succeed in regaining their own country, Rory would be able to live all his days in peace and comfort, independent of the whims of his Irish tenantry, and Allan—ah, yes, poor Allan!—began to dream of home now. Already, in imagination, he saw Glentruim a fair and smiling valley, every acre of it tilled, comfortable cottages sending their blue smoke heavenwards from the green birchen woods, a new and beautiful church, and the castle restored, himself once more resuming his rights of chief of his clan, and his dear mother and sister honoured and respected by all.

“I’ll roast an ox whole, boys!” he cried, one evening, jumping up from the sofa in the snuggery, where he had been lying thinking and dreaming of the future. “A whole ox; nothing less!”

Rory and Ralph burst out laughing.

“A vera judeecious arrangement!” cried Sandy. “But where will ye get the ox? I’m getting tired o’ bear-beef, and wouldn’t mind a slice out of a juicy stot’s rump.”

“Oh, dear!” said Allan, smiling; “I forgot you hadn’t been following the train of my thoughts. I was back again in Arrandoon.”