a hoop having a circular cross section of the relatively insignificant diameter of 7,900 miles-these amazing numbers of meteors are annually encountered and for the most part consumed as they pass through our air; and yet there is seemingly no diminution in the supply. If we suppose that the space between the Earth's orbit and the Sun is supplied with equal richness, then undoubtedly we already begin to have evidence of some such solar appendage as we have supposed the corona to be. But this is not all. We know that the meteor systems which cross our Earth's orbit have paths of great eccentricity, so eccentric in some cases as to carry the members of these systems much farther out into space than the orbit of distant Neptune. We know certainly therefore that the intersection of any meteor-orbit with our Earth is a mere coincidence; a coincidence which would be so unlikely, if there were but a few millions of such systems, that the laws of probability force on us the conclusion that there must be millions of millions of meteoric systems for each encountered by the Earth. We know again that, according to the laws of motion, the existence of multitudes of eccentric systems implies necessarily the aggregation of meteors in the Sun's neighbourhood.*

This is true, notwithstanding the fact that in any single meteoric system, elliptical in figure, the average condensation (in long intervals of time) must be least near the Sun, owing to the relatively swift motions of the meteors there. For if we conceive the case of a vast number of eccentric meteoric systems in every variety of position, the diminution of aggregation due to this cause would be as the distances; but the increase of aggregation due to the volumetric diminution of concentric

On this account alone the average density of meteoric aggregation would be twice as great at half the Earth's distance, three times as great at one-third the Earth's distance, and so on.

But further, meteors have been found to be associated with comets-in this way-that the only meteor systems whose orbits have been determined travel on the orbits of known comets. If we assume this relation, observed in the only instances we have yet had the opportunity of examining, to apply generally, then we must infer a yet greater increase of meteoric aggregation near the Sun. For it has been shown that cometic perihelia aggregate more and more densely the nearer we approach the Sun.

Yet further, it would seem from the researches of Leverrier into the motions of the planet Mercury, that within the orbit of that planet there must be an increased aggregation of matter. For he has shown that certain perturbations of Mercury's motion may be explained by the existence of several small planets travelling around the Sun within the orbit of Mercury; and as we have had no proof of the existence of even a single object of this class, and as the observed effects can be equally well accounted for by the supposition that myriads of much minuter bodies exist, we may fairly infer on this account alone that the neighbourhood of the Sun is richly peopled with minute cosmical bodies.

shells of equal thickness around the Sun with approach to him, would be as the square of the distance. Hence results on the whole an average increase of aggregation proportional to the diminution of the distance.

Yet once more, Baxendell of Manchester has proved that certain periodic meteorological phenomena, detected by him in the tabulated statements of the best observatories, can be explained by the theory that there exists around the Sun a ring or zone or spheroid of matter (his theory does not insist, he says, on any special form) at about that same distance from the Sun which Leverrier has assigned to the family of intra-mercurial planets.

Assuming that the meteoric families which undoubtedly exist, and undoubtedly become more densely aggregated with approach towards the Sun, do thus-as Leverrier's theory and Baxendell's would alike suggest -grow even yet richer at about that distance from the Sun to which the corona extends when most favourably seen, we have this also to further strengthen our belief in the resulting brightness of the solar appendage thus formed that these meteors would be severally illuminated with inconceivable splendour on account of their nearness to the Sun. If we add to this that those approaching most nearly to him would be rendered incandescent, if not vaporised, by the intensity of his heat, and that most probably electric discharges would take place between them on account of the intense

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I am aware that under ordinary terrestrial conditions the electric discharge will not take place through a vacuum. But we have no evidence that an actual vacuum exists where the corona is seen. the contrary, it is probable that multitudes of the minute bodies travelling past the Sun become vaporised, and so combine to form a moving vaporous region, whose constituent parts are continually changing as fresh matter arrives and as portions pass away to distances where they

energy of the solar action, we have, I think, abundant reason for expecting that when the Sun undergoes eclipse an aureola of splendour would be seen around him.

We have, then, two distinct lines of argument. We have been led by the consideration of the phenomena actually presented by the corona to the conclusion that multitudes of bodies too minute to be separately visible exist around the Sun; while we have been led by the consideration of what we know respecting multitudes of minute bodies actually travelling around the Sun to the conclusion that a corona or aureole of light would be seen around him during total eclipse. It seems clear, too, that all those peculiarities of the corona which have seemed to oppose themselves so obviously to other theories accord most perfectly with this. Save, perhaps, one only. If the corona is really crossed by radiating dark bars such as are shown in Mr. Gilman's picture, and described by several observers of total eclipses, then most certainly that phenomenon is not accounted for by the theory here put forward. The meteoric theory will account for a radial dark bar-by which I mean a bar directed in a straight line from the Sunas an occasional phenomenon. But that such bars should be a characteristic phenomenon of the corona, or that in any single case the corona should be seen

can resume their normal condition. Changes also occur, in all probability, which no physical researches yet made can explain, since we have proof of peculiar forms of action in the formation and rapid growth of cometary appendages.

streaked with several such bars, is a phenomenon which nothing in the meteoric theory considered per se is calculated to explain.

Now this is a difficulty which must be faced by some better means than a mere attempt to negative the evidence. That erroneous observations are made from time to time is unfortunately true; but when a characteristic phenomenon which does not seem likely to be merely imagined, is attested by trustworthy observers, a theory begins to wear a most questionable aspect which can only be supported by assigning those observations to illusion.

The difficulty in this case is that, even setting aside the objections (overwhelming as I think) which have been brought against all other theories but the meteoric one, we do not find in any of these theories the means of explaining this particular phenomenon.

Certainly no theory involving the existence of a lunar atmosphere can aid us in this strait; because if the radial bars were due to the passage of the solar rays straight through such an atmosphere in lines touching the Moon's edge (and no other path would account for the observed phenomenon), then the extension of the lunar atmosphere necessary to account for the observed appearances would be about 200,000 miles, or the lunar atmosphere would extend nearly to the Earth.* We cannot for a moment imagine this.

*It is easy to see this by making a diagram showing the Moon and Earth, with the paths of the imagined rays extending along the boundary of the Moon's geometrical shadow, carrying the rays on until, as seen from the station of an observer on the Earth (and within the shadow

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