hollow sounds at the Solfaterra, near Naples, from which travellers have inferred the existence of cavities within the mountain. At the place where these sounds are heard the earth is friable, and, when struck, the concussion is reinforced and lengthened by the partial echoes from the surfaces of the fragments. The conditions for a similar effect exist upon the glacier, for the ice is disintegrated to a certain depth, and from the innumerable places of rupture little reverberations are sent, which give a length and hollowness to the sound produced by the crushing of the fragments on the surface. We looked to the sky at intervals, and once a meteor slid across it, leaving a train of sparks behind. The blue firmament, from which the stars shone down so brightly when we rose, was more and more invaded by clouds, which advanced upon us from our rear, while before us the solemn heights of Monte Rosa were bathed in rich yellow sunlight. As the day advanced the radiance crept down towards the valleys; but still those stealthy clouds advanced like a besieging army, taking deliberate possession of the summits, one after the other, while gray skirmishers moved through the air above us. The play of light and shadow upon Monte Rosa was at times beautiful, bars of gloom and zones of glory shifting and alternating from top to bottom of the mountain. [Sidenote: ADVANCE OF THE CLOUDS. 1858.] At five o'clock a gray cloud alighted on the shoulder of the Lyskamm, which had hitherto been warmed by the lovely yellow light. Soon afterwards we reached the foot of Monte Rosa, and passed from the glacier to a slope of rocks, whose rounded forms and furrowed surfaces showed that the ice of former ages had moved over them; the granite was now coated with lichens, and between the bosses where mould could rest were patches of tender moss. As we ascended, a peal to the right announced the descent of an avalanche from the Twins; it came heralded by clouds of ice-dust, which resembled the sphered masses of condensed vapour which issue from a locomotive. A gentle snow-slope brought us to the base of a precipice of brown rocks, round which we wound; the snow was in excellent order, and the chasms were so firmly bridged by the frozen mass that no caution was necessary in crossing them. Surmounting a weathered cliff to our left, we paused upon the summit to look upon the scene around us. The snow gliding insensibly from the mountains, or discharged in avalanches from the precipices which it overhung, filled the higher valleys with pure white glaciers, which were rifted and broken here and there, exposing chasms and precipices from which gleamed the delicate blue of the half-formed ice. Sometimes, however, the _neves_ spread over wide spaces without a rupture or wrinkle to break the smoothness of the superficial snow. The sky was now for the most part overcast, but through the residual blue spaces the sun at intervals poured light over the rounded bosses of the mountain.