Whilst we lay at work, the sound of falling water in the depths below broke on our ears, a musical but ominous salutation. The obstacle wasted two hours of valuable time. Wriggling through at last, feet foremost, our legs came out over the rift, a narrow chasm some 20 feet deep, with the head stream of the cavern tumbling in over a choke-stone at one end. Our goods were let down carefully into the hands of the first man, who lodged them in a sheltered spot whilst we scrambled hastily down through showers of spray. Now began a painful advance into the depths. Along the tilted bedding planes, down the perpendicular joints of the Limestone, widened by the water into broad, low chambers and deep shafts and canyons, we forged ahead, hugging the stream, which grew larger and angrier as tributaries came swishing in from walls and roof. At one point the water swept horizontally along a straight canal, but was stopped at the end by a recent choke, and now tumbled through a hole in the wall into a huge pothole. Through this lay our road. [Illustration: ENTRANCE OF SWILDON'S HOLE. _Photo by M. Martel._] [Illustration: WATERFALL, SWILDON'S HOLE. _Photo by H. E. Balch._] The water poured down a staircase of similar basins, where to keep clear of the stream was impossible. So far we had kept tolerably dry, but as we clung to this watery ladder I pricked up my ears at the remark, "Will you have your back or your stomach in it?" Crouching on all fours, with back pressed against the low roof, and looking between my legs, I watched the performances of my comrades, as each in turn went through the final archway. Not one escaped a severe wetting. But I was going to be more wily--at least, I thought so. With hands and knees in the rushing stream, I squirmed hastily but cautiously through. I seemed to be getting on famously, and gave a spurt. That moment the rocks ended; they were undercut. I found myself sliding down a waterfall 10 feet high, and floundering in a big pool at the bottom. Drenched we were; but what better preparation could we have for the troubles ahead? This part of the cavern shows traces of enormous changes in the course of the stream, which has planed down great masses of stalagmite, the growth of ages, when this section of the tunnels was dry or all but deserted by the streams, which found a way down by the horizontal canal or some higher channel. Between this first water-chute and the second lies the most nerve-trying part of the journey to the farthest point hitherto attained. It is a succession of lofty rifts, giving into each other at right angles, the water sweeping from one to the next through curving fissures and sudden falls. For a while we kept above the canyons on a water-worn shelf, all that remained of a low, flattish chamber that sufficed for the small streams of older times. This giving out, we scrambled along the cliffs of the canyons, which seemed in the gloom without top or bottom, bestraddling the rift, or