often manages to thrust us right out of our orbits—a feat which even the wretched little planetoids, of whom myriads might find room in the head, millions in the tail, of one of us, have sometimes succeeded in performing. I would not, however, have you believe that we are mere “visible nothings”—the “airy offspring of vapour and the sun;” however so attenuated the material composing us may be, still it is ponderable matter; and there can be no doubt but that in some of us at least, the nucleus consists of a solid body of appreciable density, a direct collision with which it would not be over wise in any planet to court. Not that I want to frighten you about the possibility of such a collision with your earth; your wise men have cleverly calculated that there are about 300,000,000 chances against a contingency of the kind. Moreover, depend upon it, none of us is likely ever to seek the chance of a brush against your earth or any other planet—and that for a sufficient reason of our own. You remember, perhaps, one of your very clever men—who, however, for all that, are by no means exempt from occasional mistakes—Mr. George Stephenson, whose genius has enabled you, poor little mites, to crawl at a somewhat less snailly pace than of old over the surface of your cheese, once said, in reply to a question addressed to him as to whether it might not be awkward if a cow were to happen to stray on a line of rails, right in the way of a rapidly-advancing train, “Yes, very awkward—for the coo!” Expe-
