Candles were now lighted, and we left the glimmer of day behind us.  A little beyond the great dome the roof became so low that we had to creep along almost on hands and knees, but it presently rose again, and to a great height.  The first obstacle—­the one that sent me back a few months before—­was a steep rock down which the water then fell in such a cascade that there was no getting a foothold upon it.  Now the water scarcely covered it, and there was no difficulty in reaching the bottom.  Here, however, was a pool through which we had to wade knee-deep.  The cavern continued, and the stalagmite became interesting by its fantastic shapes.  Here was a mass like an immense sponge, even to the colour, and there, descending from the roof down the side of the rock, was the waved hair of an undine that had been changed into white and glistening stone.  The stalactites were less remarkable.  The sound of dropping water told us that another cascade was near.  This we left behind by climbing along the side of the gallery, clinging to the rock, and in the same way four more obstacles of precisely the same character were overcome.  All the distance the slope was rapid, but at intervals there was a sudden fall of from ten to fifteen feet, with a black-looking pool at the foot of the rock, hollowed out by the action of the tumbling torrent.  The last of these falls was the worst to cross.  To this point the cavern had been already explored, but no farther apparently, the local impression being that it ended just beyond.  It was an ugly place.  The rock over which the water fell was almost perpendicular, and the pool at the bottom was larger and deeper than the others.  Seen by the light of day, any schoolboy might have scoffed at the difficulty of getting beyond it, but when you are descending into the bowels of the earth, where the light of two candles can only dissolve the darkness a few yards around you, every form becomes fantastic and awful, and the effect of water of unknown depth upon the imagination is peculiarly disturbing.  But we made up our minds to go on if it were possible.  The passage was very narrow, and the sides offered few salient points to which one could cling.  We moved along a very narrow ledge in a sitting posture, and then, when we had gone as far as we could in this way, and there was nothing beyond to sit upon, we made a spring.  My companion, being the more agile, nearly cleared the pool, but I went in with a great splash, as I expected, and thought myself lucky in being only wetted to the waist.  The water was not very cold, the temperature of the cavern being much higher than that of the outer air.

We reckoned that we had by this time travelled underground about half a mile, and as we had been descending rapidly all the way, the distance beneath the surface must have been considerable.  My theory with regard to this stream was that it was a tributary of the subterranean Ouysse; but the fact that the cavern ran north-west made me change my opinion, and conclude that this water-course took an independent line towards the Dordogne.