“Hurry up, boys!” he shouted.
The words had scarcely left his lips when there was a tremendous crash, and the delicately balanced upper rock came down, filling the entire opening and leaving them in utter darkness.
The roar was deafening in that confined space, and beat upon their eardrums until it seemed as though they would burst. And a cloud of dust arose that was suffocating.
The captain, inured to dangers and to quick thinking, was the first to realize what had happened.
“Trapped!” he roared. “Trapped! Penned in like so many rats!”
He rushed against the heavy stone and heaved against it with all the strength of his powerful shoulders. But strain as he would, he could not make it budge. And as he remembered its giant size, he realized that it must weigh scores of tons. He might as well have tried to move a mountain.
As this conviction came to him, he desisted from his efforts and came slowly towards his companions.
“Lucky that the boys are not in here with us,” he remarked, his habitual calmness returning to him. “They, at least, have their chance. It is singular, too,” he mused. “Don, especially, is usually right up to the front at a time like this. Didn’t you think they were following us?”
“I thought I heard them answer you when you called to them,” replied the professor. “But, after all, that may have been only the echo of your voice.”
“Possibly,” rejoined the captain. “But, at any rate, they must be right outside now. We must communicate with them and get them to go to Ismillah and Abdul for help. With our united efforts, we may be able to make an exit.”