Page:Popular Science Monthly Volume 64.djvu/230

226 over the mountain slopes light down to the sea. It was dull red and in it were brighter streaks thought to be large stones, as they seemed to give off tails of yellow sparks. They bowled along apparently rebounding when they struck the surface of the ground. The dark-red avalanche had a billowy surface, and its velocity was tremendous. "The mist and steam on the mountain top did not allow us to see very clearly how the fiery avalanche arose, but we had' a perfect view of its course over the lower flanks of the hills, and its glowing, undulating surface was clearly seen." The red glow faded in a minute or two, and a round black boiling cloud rushed over the sea in front of it, filled with lightnings. This cloud was globular as seen end on, very perfectly rounded, covered with innumerable minor rounded excrescences which were filled with terrific energy. It was full of short lightnings—'A mere succession of flashing points in the great black wall of cloud.' "Many of the flashes were horizontal, others shot obliquely from one lobe to another, while along the base where the black cloud rested on the steel-gray sea, there was a line of sparkling light. constantly changing, varying in amount, but never disappearing."

A gentle puff of wind came from the southeast. The cloud lost its violence and became a gigantic wall with a velvety appearance in the moonlight, resembling a black curtain draped in folds. In size it was estimated to be two miles broad and about one mile high. The