Gilbert, whose turn it was to be in charge of the ship’s movements, said not a word, but walked across to the switchboard and made some slight alteration, then came amongst them again. Scarcely had he resumed his position when, with the suddenness of a pistol-shot, they were plunged into darkness—a darkness that could be felt. Willing hands excitedly drew up the screens, but all outside was dense blackness; the inner lights were put on, but only the inside of the net was visible through the glass, and Ross at once switched on the whole of the search-lights, which blazed forth in all directions, revealing dense and impenetrable fog on every side. “What has happened? Where are we?” every one was asking, in consternation. “I don’t know!” replied Gilbert, looking at the dial and the distance travelled; “the ship is all right; we are still falling rapidly, but we’re not in the sun, that’s evident!” And he brought the vessel to a stand, poised in equilibrium, wherever they might be. CHAPTER XIII “VAULTS OF PURPLE” “All the elements At least had gone to wreck, disturbed and torn With violence of this conflict.” (+Milton.+) “What’s up, old man?” exclaimed Ross, hurriedly, as he and Dennis came hastily round the barrier, and Dennis asked, “Anything gone wrong?” “Not here!” replied Gilbert, mystified; “the ship’s all right, everything is in perfect order and working splendidly. What’s gone wrong we’ve to find out. We have come on a straight line towards the centre.” “Have we gone off at a tangent and come outside?” asked Miles Dalton, a botanist, as the rest all crowded up to the barrier. “Impossible!” replied Dennis, “or we should again be in the atmosphere, or photosphere.” “We must do something!” said Gilbert; “shall we sample the fog outside with one of the strong retainers, and risk another explosion?” All the others assenting, he continued: “Here, Dennis, take my place, old man, and do something for your living! that job can wait, under the circs.!” And he and Price Rowland passed into the laboratory. The ship being safe, the others all stood about discussing the curious situation, without arriving at any reasonable conclusion. In the meantime, Gilbert and Rowland had obtained a sample of the outer air, this time without accident, and in due course they entered the saloon, where all the others crowded round them, anticipating startling news from their surprised expressions. “What do you think!” exclaimed Gilbert; “the atmosphere here is nitrogen, neither more nor less than pure nitrogen!” Had he told them they were in the shed at home, his fellow travellers could not have been more astonished, and several incredulously repeated, “Nitrogen? _nitrogen!_ are you sure? Nitrogen!!—a colourless gas, and this colour!”