"It is the incense," was the reply. "Come! The worst of our task is before us yet."
The continuation of the passage now showed as an opening no more than fifteen to seventeen inches high. It was necessary, therefore, to lie prone upon the rubbish of the floor, and to proceed serpent fashion; one could not even employ one's knees, so low was the roof, but was compelled to progress by clutching at the irregularities in the wall, and by digging the elbows into the splintered stones one crawled upon!
For three yards or so they proceeded thus. Then Dr. Cairn lay suddenly still.
"What is it?" whispered Sime.
A threat of panic was in his voice. He dared not conjecture what would happen if either should be overcome in that evil-smelling burrow, deep in the bowels of the ancient building. At that moment it seemed to him, absurdly enough, that the weight of the giant pile rested upon his back, was crushing him, pressing the life out from his body as he lay there prone, with his eyes fixed upon the rubber soles of Dr. Cairn's shoes, directly in front of him.
But softly came a reply:
"Do not speak again! Proceed as quietly as possible, and pray heaven we are not expected!"
Sime understood. With a malignant enemy before them, this hole in the rock through which they crawled was a certain death-trap. He thought of the headless bats and of how he, in crawling out into the shaft ahead, must lay himself open to a similar fate!
Dr. Cairn moved slowly onward. Despite their anxiety to avoid noise, neither he nor his companion could control their heavy breathing. Both were panting for air. The temperature was now deathly. A candle would scarcely have burnt in the vitiated air; and above that odour of ancient rottenness which all explorers of the monuments of Egypt know, rose that other indescribable odour which seemed to stifle one's very soul.