Two of us now went off on an exploring trip into the great passage running west. At once we encountered a series of huge obstructions. This passage was of the usual rift pattern, and, save for holes and crevices between, was wholly blocked up by large masses of tumbled rocks. One of us climbed to the top of the Cyclopean pile, whilst I attempted to make my way along at the middle height, but eventually found it easier to crawl through the culverts and water-gaps, regardless of mud and wet. Even among the piled-up rocks there were charming little nooks adorned with rich incrustations. When the rocks ended the open tunnel began to ascend rapidly; then, after a while, we came to another tunnel joining it on the north. This, though smaller, was the more important passage; the other shortly came to an end in a lofty grotto, bountifully tapestried with curtains and tassels of stalactite. We climbed the northern passage, through several brilliant displays of incrustation, and reached a level approximately 70 feet below the surface, by aneroid; there we could get no farther. But, unknown to ourselves, we had brought back important information. We had noticed mysterious bits of string at two points in this series. When we reported the discovery to the two men left behind, they at once saw its significance. The two men whose route down to the stalactite chamber had caused so much perplexity had used a ball of string to mark their way out--these were the relics. Our casual trip had, perhaps, saved us from a night of blind wandering in the unknown branches of the great tunnel on the north. All being in readiness for our departure, we now proceeded to take up this providential thread. It was not an easy task. Often not an inch of string remained undecayed for many hundreds of feet together, and often we nosed the walls and floor, eagerly but in vain, for droppings of candle grease left by our predecessors. The way was dry, that was a relief, after six or seven hours in wet clothes; but it was a tighter squeeze than the other, and the sharpness of the turns was often aggravated by a portcullis of crystals on our backs, and a _cheval de frise_ of stalagmite spear-heads against our stomachs. All the while we wondered whether we should really find the exit, or whether we should have to return and undertake the canyons after all. Mr. Balch compared our task of finding the desired exit to an attempt to ascend from the mouth of a river to some unknown point upon one of its tributaries, with nothing to indicate which way to take. This puts the position clearly enough, I think. There was no string to be found in the higher parts. At last the man in front disappeared feet foremost through the ugliest hole we had yet seen, out of which the noise of waters sounded ominously. A cheering cry came back to us; he had found the rift, where we had descended seven hours ago into the route through the canyons. A few more yards of determined