The Underground Bridge is not a brilliant achievement in engineering, but seems to be well constructed and safe, which is an important consideration; for, although it is so many hundred feet below the summit of the mountain, and yet down so low as to be on the same level as the foundations of the Cave House in the adjacent valley, it spans a black yawning gulf, at the extremity of which, 50 feet still farther down, is a clear pool of water 20 feet deep! The Bridge is about 42 feet long. It has wire girders and uprights, with stanchions and handrails, and a wooden deck, which, by-the-bye, needs some repair, for several of the planks are broken. The passage is made increasingly secure by galvanised wire netting stretched along the lower part of the Bridge on both sides. The rocks which form the boundary of the immense chasm spanned by the Bridge are of enormous size, and the scene from this point is remarkable for sublimity rather than for what is commonly called beauty. Near the roof is an immense recess, filled with huge stalactites and mammoth pieces of formation, which have floated over the bottom and formed graceful ornamentation for the cavern below. And so the process is repeated from the top of the immense chamber, near the roof, down to the rugged walls immediately round the Bridge. Even on the rocks which surround the abyss similar wondrous decorations are lavishly bestowed. The clear-headed and sure-footed guide descends from one jutting rock to another and yet another, until he approaches a row of remarkable stalactites which can be just discerned through the gloom. This group is called "The Piano," because of the resonant qualities of its separate parts. Each stalactite gives out a note. The notes vary in quality and pitch, but most of them are imperfect. As stalactites they are very fine, but as melodious instruments they are frauds. They refuse to harmonise, and their music is about as entrancing as that of a discordant "upright grand," mounted on one leg and played with a handle. CHAPTER XII. THE LURLINE CAVE. Seventy or eighty yards from the Underground Bridge is the Lurline Cave. The course is south-west, through a curved gallery with 53 steps in different flights, and two archways--one like loveliness when "adorned the most," and the other formed by an ornate mass of stalactites.