This brings us to an altitude of fifty thousand feet above the level of the ocean, and next comes the region of precipices which stretch up to the cloud-screen. This final ascent is divided into three gigantic steps; the first, and smallest of them, about ten thousand feet high, leads to a wide plateau; next comes the most awful of the three, not less than thirty thousand feet, terminating in a much narrower terrace, from which starts the last of the steps. This is not exactly a precipice, but a slope of seventy-five degrees; about fifteen thousand feet of this are visible; it then enters the cloud and is lost to view. The above description has, I trust, made it manifest that an attempt to reach the screen by the mountain route would prove a very arduous undertaking. Vast labour and cost would be essential, and here the advantages of the great world-parliament became exceedingly conspicuous. The enterprise was cheerfully voted to be a world-work. There was no fear that it would come to an untimely end through lack of any material supplies. A committee of the ablest engineers was appointed to examine and report on the most favourable spot for commencing operations. They were not long in coming to an unanimous decision, and the works began. It was resolved to drive a tunnel the whole way from the table-land under the glacier as far as its upper edge. This formidable work was found to be quite indispensable, in consequence of the incessant avalanches and ice-falls which, issuing from the glacier, fell down the steep slope to the table-land. Indeed, they were obliged to start the tunnel at a distance of fully five miles from the foot of the slope, as a security against the blocking of the entrance. Running nearly horizontally for these five miles, it then bent upwards at an angle of forty-five degrees, and, after a total rise of thirty thousand feet, issued at the top of the glacier, close to the foot of the first step in the series of precipices. The excavation of this tunnel, which was nearly thirteen miles long, was an exceedingly formidable task. But it was undertaken with such zeal and energy, and carried on with such perseverance, that the seemingly insuperable obstacles were at last overcome. Gangs of experienced miners, superintended by skilful engineers, relieved each other, night and day, at the work. Every material required was supplied in profusion. The new dynamical agent which had supplanted the vapour of water as a motor force, had been rendered available for instantaneous percussive action, after the manner of gunpowder, but with incomparably greater energy; and this was extensively utilised for the removal of the rocks. Still, as it was not possible to work at the tunnel except on one face, several years elapsed before the miners emerged into daylight at the top of the glacier.