Starting up, he sprang into the large cavern where he found Van der Kemp quietly tightening his belt and Moses hastily pulling on his boots.

“Sometin’s bu’sted an’ no mistake!” exclaimed the latter.

“An eruption from one of the cones,” said the hermit.  “I have been for a long time expecting it.  Come with us.”

He went swiftly up the staircase and passages which led to the observatory as he spoke.

The scene that met their eyes on reaching the ledge or plateau was sublime in the extreme, as well as terrific.

“As I thought,” said Van der Kemp, in a low tone.  “It is Perboewatan that has broken out.”

“The cone from which I observed smoke rising?” asked Nigel.

“The same.  The one over the very centre of the old crater, showing that we were wrong in supposing it to be extinct:  it was only slumbering.  It is in what vulcanologists term moderate eruption now, and, perhaps, may prove a safety-valve which will prevent a more violent explosion.”

That the cone of Perboewatan was indeed in a state of considerable activity, worthy of a stronger term than “moderate,” was very obvious.  Although at a distance, as we have said, of four miles, the glare of its fires on the three figures perched near the top of Rakata was very intense, while explosion after explosion sent molten lava and red-hot rocks, pumice, and dust, high into the thickening air—­clouds of smoke and steam being vomited forth at the same time.  The wind, of which there was very little, blew it all away from the position occupied by the three observers.

“What if the wind were to change and blow it all this way?” asked Nigel, with very pardonable feelings of discomfort.

“We could return to the cavern,” said the hermit.

“But what if Rakata itself should become active?”

It was evident from the very solemn expression on the negro’s face that he awaited the reply to Nigel’s question with some anxiety.

“Rakata,” answered the hermit thoughtfully, “although the highest cone, is the one most distant from the great centre of activity.  It is therefore not likely that the volcanic energy will seek a vent here while there are other cones between us and Perboewatan.  But we shall soon see whether the one vent is likely to suffice.  There is undoubtedly no diminution in the explosions at present.”

There certainly was not, for the voice of the speaker was almost drowned by the horrible din caused, apparently, by the hurtling of innumerable fragments of rock and stones in the air, while a succession of fiery flashes, each followed by a loud explosion, lit up the dome-shaped mass of vapour that was mounting upwards and spreading over the sky.  Vivid flashes of lightning were also seen playing around the vapour-column.  At the same time, there began a fall of fine white dust, resembling snow, which soon covered the foliage and the ground of all the lower part of the island.  The sea around was also ere long covered with masses of pumice, which, being very light, floated away into the Indian ocean, and these were afterwards encountered in large quantities by various vessels passing through Sunda Straits.