According to his theory, Tschermak, noting the resemblance of structure between meteorites and volcanic products, suggests that meteors of all orders (which would include meteor streams, and therefore comets) were shot out from the earth in the days when she was young. But though this is better than the other theories, in at least suggesting some sort of an origin for comets and meteors, it will not account for comets which do not approach within many millions of miles of the earth’s orbit,[12] and a theory which fails for some among the comets cannot be the true general theory for meteors either. Mr. Sorby of Sheffield, the eminent mineralogist already referred to, deduced from the microscopic structure of certain meteorites the startling theory that they had once been inside the sun; for there is evidence that their substance once existed in the form of globules of molten metal, which aggregated with large masses, which in turn were exposed to violent friction, indicating conflicting motions of very high velocities. “Where else,” wrote Sorby, in 1864, “could such conditions exist, except first in the interior, and afterwards in the immediate neighborhood of our sun!” But it is absolutely certain that the theory as thus suggested cannot possibly be true, either as a general explanation of comets and meteors, or even as an explanation of any known meteor system or comet, unless, perhaps, a few of the comets whose orbits pass very near the sun were sun-born, and subsequently disturbed by planetary attractions so as not to return to their parent orb. According to my father’s views on the subject: “A flight of meteors shot out from the sun, as Sorby suggested, might have velocity enough to get away from him forever, in which case we should never see a trace of it again, even though we waited for millions of years. If, however, it could not get away, then it must return to its starting-place—that is, back to the sun’s globe—unless, passing near enough to one of the giant planets, it were so far disturbed as only to return by grazing past the sun’s surface. (The comets of 1843, 1880, and 1882, which all traveled in paths near the sun, almost grazing his surface, may well have been parts of a single meteor-flight shot out from his interior millions of years ago.)” After the appearance of the new comet of 1887 in the southern skies, it was found to be following along the same track as the comets of 1843, 1880, and 1882, thus confirming my father’s theory that these comets were parts of one large comet, dissipated, doubtless, some millions of years ago. These comets were so bright when near the sun that they could be seen at noon with the naked eye. As regards the heat experienced by the comet of 1843 when near the sun, Sir John Herschel remarked: