By quite another class of dark bodies than those we contemplated in the last chapter is the immediate space about us tenanted. For that, too, is anything but the void our senses give us to understand. Could we rise a hundred miles above the Earth’s surface we should be highly sorry we came, for we should incontinently be killed by flying brickbats. Instead of masses of a sunlike size we should have to do with bits of matter on the average smaller than ourselves but hardly on that account innocuous, as they would strike us with fifteen hundred times the speed of an express train. Only in one respect are the two classes of erratics alike, both remain invisible till they are upon us. Even so, the cause of their visibility is different. The one is announced by the light it reflects, the other by the glow it gives out on its destruction. These last are the meteorites or shooting-stars. They are as well known to every one for their commonness as, fortunately, the first are rare. On any starlight night one need not tarry long before one of these visitants darts across the sky, a brilliant thread of fire gone almost ere it be descried. Usually this is all of which one is made aware. Silent, ghostlike, the apparition comes and goes, and nothing more of it is either seen or heard. But sometimes there is a good deal more. Occasionally a large ball of flame shoots through the air, a detonation like distant thunder startles the ear, and a luminous train, persisting for several seconds, floats slowly away. Finally if one be fortunate to be near,—but not too near,—one or more masses of stone are seen to fall swiftly and bury themselves in the ground. These are meteorites: far wanderers come at last to rest in graves they have dug themselves. A great revolution has taken place lately in our ideas concerning meteorites. Indeed, it was not so very long ago, since modern man admitted their astronomic character at all. He looked as askance at them as he did at fossils. It was the fall at Aigle, in Switzerland, April 26, 1803, that first opened men’s eyes to the fact that such falls actually occurred. It is more than a nine days’ wonder at times how long men, as well as puppies, can remain blind. To admit that stones fell from heaven, however, was not to see whence they came. Their paternity was imputed to nearly every body in the sky. They were at first supposed to have been ejected from earthly volcanic vents, then from volcanoes in the Moon. That they are of domestic manufacture is, however, negatived by the paths they severally pursue. Nor can they for like reason have been ejected from the Sun.