Many of them were as perfectly round as though cast in a mould, others were egg-shaped, and all were hollow.

With some difficulty I broke them, and found them to contain a bright red sand.

They were, in fact, volcanic bombs that had been formed by the ejection of molten lava to a great height from active volcanoes; these had become globular in falling, and, having cooled before they reached the earth, they retained their forms as hard spherical bodies, precisely resembling cannon shot.

The exterior was brown, and appeared to be rich in iron.

The smaller specimens were the more perfect spheres, as they cooled quickly; but many of the heavier masses had evidently reached the earth when only half solidified, and had collapsed upon falling.