The magnificence of that one chamber should give to Marble Cave a world-wide fame even if there were nothing more beyond. The blue-gray limestone walls have a greater charm than those of an open canon, owing to the fact that they sweep away from any given point in long, true curves to form an elliptical chamber three hundred and fifty feet long by one hundred and twenty-five feet wide, with the vault above showing absolute perfection of arch, and measuring, by the survey, from its lowest to its highest point, one hundred and ninety-five feet. These measurements are said to be indisputably correct, and if so, the Auditorium of Marble Cave is the largest unsupported, perfect arch in the world; it being one hundred feet longer than the famous Mormon Tabernacle at Salt Lake City. In addition to the artistic superiority of architectural form, its acoustic properties having been tested, it is found to be truly an auditorium. The curving walls and pure atmosphere combine to aid the voice, and carry its softest tones with marvelous distinctness to every portion of the immense inclosed space. As a concert hall its capacity has been tested by musicians who are said to have been enthusiastic over the success of their experiments. Several years ago a piano was lowered into the cave for use on a special occasion, and still occupies a position on the dancing platform, where it will probably remain indefinitely under the scant protection of a small canvas tent. The chief ornament of the Auditorium is the White Throne, a stalagmitic mass that when viewed from the stairway appears to rest solidly against the most distant wall, and looks so small an object in that vast space as to render a realization of its actual measurement impossible. The height of the Throne is sixty-five feet and the girth two hundred. It is a mass of dripstone resting on a limestone base reserved from the ancient excavation to receive it, and on careful inspection the perpendicular lines, observed on the front, are found to be a set of rather large organ pipes. A fresh fracture shows the Throne to be a most beautiful white and gold onyx. The outer surface has now received a thin coating of yellow clay which was, of course, regretted, but later observations on onyx building reveals the pleasing fact that if the crystal-bearing waters continue to drip, the yellow clay will supply the coloring matter for a golden band of crystal.