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 dynamics are fortunately available, and though they do not, it is to be regretted, convey all that we should like to know, yet still they teach us something with regard to the movements of the meteorites, and thus conduce to the solution of the great problem of their origin.

I am fully aware that there is considerable diversity of opinion as to the origin of meteorites. To me, however, it appears that the source of these bodies ought not to be a matter of much uncertainty. At the commencement of the inquiry it will be well to remove what is, I believe, a not uncommon misconception with regard to the character of meteorites. There can be no doubt that one of these bodies is often accompanied in its descent to the earth by a flash of fire, and not unfrequently a loud detonation announces at the same time that some violent disruption of a mass of matter has taken place. To this extent the fall of a meteorite presents phenomena resembling those which often accompany the apparition of a great fire-ball. In fact I suppose it can hardly be doubted that many of the fire-balls not recognised as meteoritic might have let fall mineral masses under somewhat different circumstances of impact upon the earth's atmosphere. But now comes one of the difficulties in the subject.

In general great fire-balls are little more than conspicuous shooting - stars, and there are shooting - stars of every dimension from those which illumine a country side with splendour down to the little streak of light which can only just be discerned as it flashes through the field of a powerful telescope. A noteworthy circumstance which interests the student of shooting-stars is their periodical exhibition in splendid displays. I allude to such a great shower as that of the Leonids which took