The cavern, into which we passed from the slippery ledge, did not lead into the interior of the mountain as one would be inclined to think after viewing it from the top of the crater.  We had hardly traversed it for more than sixty yards when we were once again in the bright sunlight, in what appeared to be a deep, wide valley in the centre of the island.  The basalt cliffs surrounded the place on every side, and although we had great doubts regarding Leith’s veracity, we felt inclined to accept his word that the path by which we had come was the only one by which we could reach the spot where we stood.  The circles of black rocks above the tops of the highest trees, though indescribably beautiful, were strangely repellent in their weird conformation.  They struck us as the walls of a prison from which the only way to liberty lay across the path in the crater.

The trees—­ebony, chatak, dakua, and sandalwood—­grew here in greater numbers than we had met them on the first day, while the lawyer-vines and thorny creepers rivalled the devilish meshes that had held us back as we climbed the slope to the Vermilion Pit.  Like green serpents they covered the treetops, and as we struck forward in the same order as we had marched on the first day the solemnity of the place was more apparent than ever.  It appeared that Nature, for some reason of her own, had made the place difficult of access, and that our invasion was something that the trees and vines protested against.

But in spite of the strange melancholy of the place, the two girls were in much better spirits than they had been on the previous day.  The successful passage over the ledge had brought about a reaction, and a remark of Holman’s caused Barbara Herndon to laugh with all the spontaneity that was noticeable upon The Waif.  The effect of that ripple of laughter was startling.  The sound rebounded from the rocky cliffs, cannoned against the barriers opposite, and then bounced backward and forward till the whole atmosphere of the valley seemed alive with the laughter of sprites.  For quite five minutes we stood listening, then the silence chased the last faint echoes out across the cliffs, and we breathed again.

“It is the Valley of Echoes,” said Leith.  “The cliffs throw back the sound in a marvellous manner.”

“I’ll not laugh again, not in this spot,” murmured Barbara Herndon.  “Those noises chilled my blood.”

In spite of a blazing sun we found the air unpleasantly cool in the shaded spots as we struggled slowly through the undergrowth.  The moist flabbiness of uncommon tropical plants startled us whenever the leaves brushed against our faces and hands, while the constant popping of the green pods of the nupu, the sounds resembling nothing so much as the groans of a person in extreme pain, did not have a cheering effect upon the party.  The Professor was the only one who seemed to be actually enjoying himself, and even his joy was tempered by a malignant Fate.  While endeavouring to dot down some information tendered him by Soma, he had tripped upon a vine that was in wait for such an opportunity, and he skinned his nose badly upon a projecting rock.