At last, just as I was thinking that I could stand it no more, the last lift came to a stand and we stepped out upon a circular platform which had been cut in the rock. I noticed that Malone gave a curiously suspicious glance round at the walls as he did so. If I did not know him to be amongst the bravest of men, I should say that he was exceedingly nervous.

'Funny-looking stuff,' said the chief engineer, passing his hand over the nearest section of rock. He held it to the light and showed that it was glistening with a curious slimy scum. 'There have been shiverings and tremblings down here. I don't know what we are dealing with. The Professor seems pleased with it, but it's all new to me.'

'I am bound to say I've seen that wall fairly shake itself,' said Malone. 'Last time I was down here we fixed those two cross-beams for your drill, and when we cut into it for the supports it winced at every stroke. The old man's theory seemed absurd in solid old London town, but down here, eight miles under the surface, I am not so sure about it.'

'If you saw what was under that tarpaulin you would be even less sure,' said the engineer. 'All this lower rock cut like cheese, and when we were through it we came on a new formation like nothing on earth. "Cover it up! Don't touch it!" said the Professor. So we tarpaulined it according to his instructions, and there it lies.

'Could we not have a look?'

A frightened expression came over the engineer's lugubrious countenance.

'It's no joke disobeying the Professor,' said he. 'He is so damn cunning, too, that you never know what check he has set on you. However, we'll have a peep and chance it.'

He turned down our reflector lamp so that the light gleamed upon the black tarpaulin. Then he stooped and, seizing a rope which connected up with the corner of the covering, he disclosed half-a-dozen square yards of the surface beneath it.

It was a most extraordinary and terrifying sight. The floor consisted of some greyish material, glazed and shiny, which rose and fell in slow palpitation. The throbs were not direct, but gave the impression of a gentle ripple or rhythm, which ran across the surface. This surface itself was not entirely homogeneous, but beneath it, seen as through ground glass, there were dim whitish patches or vacuoles, which varied constantly in shape and size. We stood all three gazing spell-bound at this extraordinary sight.

'Does look rather like a skinned animal,' said Malone, in an awed whisper. 'The old man may not be so far out with his blessed echinus.'

'Good Lord!' I cried. 'And am I to plunge a harpoon into that beast!'

'That's your privilege, my son,' said Malone, 'and, sad to relate, unless I give it a miss in baulk, I shall have to be at your side when you do it.'

'Well, I won't,' said the head engineer, with decision.

'I was never clearer on anything than I am on that. If the old man insists, then I resign my portfolio. Good Lord, look at that!'

The grey surface gave a sudden heave upwards, welling towards us as a wave does when you look down from the bulwarks. Then it subsided and the dim beatings and throbbings continued as before. Barforth lowered the rope and replaced the tarpaulin.

'Seemed almost as if it knew we were here,' said he.

'Why should it swell up towards us like that? I expect the light had some sort of effect upon it.'

'What am I expected to do now?' I asked. Mr. Barforth pointed to two beams which lay across the pit just under the stopping place of the lift. There was an interval of about nine inches between them.

'That was the old man's idea,' said he. 'I think I could have fixed it better, but you might as well try to argue with a mad buffalo. It is easier and safer just to do whatever he says.