Acting on the professor's advice the aeroplane was grounded at a point some distance from the summit of the mountain, on a small flat plateau. The warmth was perceptible, and some few stunted bushes and trees clung to the sides of the flaming mountain. The professor was delighted to find, flitting among the vegetation, a small fly with pink and blue wings, which he promptly christened the Sanburritis Antarcticitis Americanus. He netted it without difficulty and popped it into a camphor bottle and turned, with the boys, to regarding the mountain.
"Let's climb it and examine the crater," exclaimed Frank, suddenly, the instinct of the explorer strong in him.
"Bully," cried Billy; "I'm on."
"And me," exploded Harry.
"I should dearly love to," spoke the professor; "perhaps we can discover some more strange insects at the summit."
The climb was a tedious one, even with the aid of the rope they had brought with them from the Golden Eagle; and with which part of the party hauled the others over seemingly impassable places. At last, panting, and actually perspiring in the warm air, they stood on the lip of the crater and gazed down.
It was an awe-inspiring sight.
The crater was about half-a-mile across the top, and its rocky sides glowed everywhere with the glare of the subterranean fires. A reek of sulphurous fumes filled the air and made the adventurers feel dizzy. They, therefore, worked round on the windward side of the crater, and after that felt no ill consequences.
For a long time they stood regarding the depths from which the heavy black smoke rolled up.
"There's no danger of an eruption, is there?" asked Billy, somewhat apprehensively.