Astronomy in the University of Chicago, must not be passed by unmentioned. It depends upon high mathematical calculations, relating to what is known as the problem of three bodies, when applied to the case of a great number of meteoric particles moving under the mutual attractions of the Sun and the Earth. Supposing certain initial conditions of motion to exist in the case of some of them, it is shown by these calculations that such particles would pause, to make one or more small curved circuits round a point, at any moment, about 900,000 miles directly beyond the Earth (in the continuation of a line drawn from the Sun), before they would pass on to continue the main part of their orbits. If, therefore, the number thus successively pausing and performing their temporary oscillations should be sufficiently great, we should constantly see in the direction oppositeto that of the Sun such an additional aggregation of particles as might produce the appearance of the Gegenschein. This suggestion is of much interest owing to its sound mathematical basis; but Dr. Moulton himself says that the question whether a sufficient number of particles could be expected so to act is one to which 'no certain answer can be given.'

In addition to all the hypotheses previously mentioned, or to avoid the necessity for any of them, it has often been wished that the Zodiacal Light could be identified with some of the immense equatorial extensions frequently seen in the Corona of the Sun during a total Solar Eclipse; as, to mention only one very notable instance, in that of July 1878. But, in a number of recent Eclipses, the most remarkable rays and extensions of the Corona have been found in directions in which they could not possibly have had any special connection with the Zodiacal Light.

If, however, in accordance with some other observations, and especially with those of M. Marchand made during the years 1892, 1893, and 1894, in the clear air of the Pic du Midi, we could definitely connect the Zodiacal Light with the plane of the Sun's Equator, instead of, as I believe most Astronomers hold, with the Ecliptic,. there might be more reason for attributing at least some part of it to a considerable amount of Coronal matter, which it is thought may be electrically ejected from the so-termed 'aigrettes,' frequently seen around the polar regions of the Sun during an Eclipse. For it is likely that such matter might find its way to equilibrium in the neighbourhood of the Sun's Equator, and be collected there, where: it would be in a region of 'zero potential.' But any such supposition must remain for the present quite doubtful, while it seems almost certain that the Gegenschein, at any rate, is localised on, or very nearly on, the Ecliptic.

Indeed, all that can be said is that nothing has been satisfactorily settled, either by observation or theory, as to any one of the three

divisions of this baffling Light. It may be connected with the Sun's Equator, or with the Ecliptic-with matter ejected from the aigrettes, or from the eruptive prominences of the Sun-or with meteoric matter circulating round the Sun, and aggregated more densely in its immediate vicinity. The main Light, and the Band, and the Gegenschein may be one phenomenon, or they may be two, or even three, independent phenomena. All of them are full of mystery still.

Nevertheless, what has thus far been accomplished gives good reason to hope that continued observations, if well arranged and carried out in suitable localities, may ere long afford some basis for a far more satisfactory theoretical study of this puzzle in our Solar System. But I believe that such observations, and plenty of them, will best precede any further theorising.

At present, so far as I can judge, the balance of probability, upon the whole, inclines to the opinion that the main Light, at least, arises from such a lens-shaped region, spreading out from the Sun, as I have repeatedly spoken of in this article. And that this region is not to be considered as occupied by any continuous matter, but by myriads upon myriads of meteoric particles, separated from one another by distances immensely great in comparison with their individual sizes; some as fine as that which we ordinarily term dust, some more like the rocky or metallic masses which frequently fall upon the Earth (at the rate, indeed, of about two a day), and which, when of greatest size and weight, are still but as dust in comparison with the bulk even of the smallest Planetoid yet known.

A view of such matter, mostly in a state of minute subdivision, is afforded to us in the millions of shooting stars which day by day enter the Earth's atmosphere. An effect of it is almost certainly felt by the planet Mercury in the perturbation of its orbital motion. The rings of Saturn are to be considered as regions of its special abundance. Comets are masses of it so loosely aggregated together that, as they journey onwards, they are constantly leaving some of it behind, until by degrees it is strewn along the whole of each Cometary path.

In addition, however, to its affording an explanation of the main Light, I cannot but hope that some such extension of this hypothesis as was published by the late Mr. Wm. Anderson in the June and August numbers of The Observatory in 1899, as the result of his many observations in Madeira, and in continuation of a paper presented to the Royal Astronomical Society in the previous year, may presently be found to show that all the three phenomena-the Zodiacal Light, the Zodiacal Band, and the Gegenschein or Counter Glow-may be attributed to one and the same disc-like collection of such matter as I have just described.

There are indications, I think, that if this disc should extend as he supposed beyond, but only to a moderate distance of some four or

five millions of miles beyond, the Earth's orbit, and if it be, as he also suggested, especially thin and sparsely constituted in its outermost parts, it may be possible to get rid of those difficulties, which have hitherto been thought to be almost insuperable, connected with the question of the Earth's immersion in it; or, if its boundaries are somewhat irregular, with the effect of the Earth's passing from time to time into and out of it.

There is, however, one remaining and important point in regard to such a collection of matter revolving round the Sun, which I venture to suggest may not hitherto have been fully considered. It is its want of homogeneity. We should naturally anticipate that the distribution of the matter would be very far from uniform. Also everywhere, even very near to the Sun, it must be allowed that it would be very sparsely scattered, otherwise it would have hindered the movement of comets, such as those of 1843 and 1882, which passed, in their perihelion passage, exceedingly near to the Solar surface. But, at intervals, groups, or streams, of particles, or meteorites, very appreciably more condensed, would almost inevitably occur. Such groups might, indeed, be comparable in character with Comets of exceeding diffuseness. At any given time such a condensation, if somewhat near to the Earth, might be revolving round the Sun with a velocity nearly the same as the Earth's. And if so, it might change its distance from the Earth quite slowly, and remain at a moderate distance from it for several consecutive months. Such a group, if of wide extent and outside the Earth's orbit, might perhaps help from time to time to give that somewhat definite apex to the main Light, which, when the Light attains to more than 90° from the Sun, is a feature for which it has been very difficult to find

a cause.

In fact, the disc-shaped region around the Sun must, I think, be occupied by multitudinous interlacing orbits of such groups of matter; some groups, no doubt, being very much smaller and sparser than others. Their varying positions and changes of aggregation may, I think, also have much to do with great differences of brilliancy in the Zodiacal Light in different years. The orbits in question need not necessarily be supposed to be circular, but might often be of a more oval form; and somewhat inclined, although probably at quite a moderate angle, to the plane of the Ecliptic.

All these considerations, and especially the apparent tendency of such matter towards the plane of the Ecliptic, lead on to one more thought of deepest moment. May we not see in this matter a remanet of our own Solar Nebula ? The matter of Saturn's Rings may well be the remanet from that part of the Solar Nebula from which the planet itself has condensed. So in like manner may that of the Zodiacal Light be a remanet of the Solar Nebula as a whole, still undergoing a process of indraught towards the Sun.

Even if, apart from its reflection to us of the Solar rays, there should be some other luminosity in all this matter, due perhaps to electrical action, such as may possibly generate much of the light of comets; or even if emanations from the Sun until recently unsuspected, such as those of Radium, may help to brighten it (as to which, however, we know very little at present); still, if this matter is the last piece of the original Solar Nebula left, its study, if successfully achieved, will teach us much as to what that Nebula is made of and what the successive stages of its past history have been. This being so, it follows that we shall thereby be the better enabled to realise what the constitution, or condition, of other Nebulæ, vaster and far more important, is, or has been, or shall be; how stars, now it may be gradually fading, have come forth in past ages from them; or even how fresh Nebula may still be evolved around us.

It is for this reason, above all others, that, as in the beginning of this article, so in concluding it, I plead that more attention may be given to the Zodiacal Light. I believe that in the very highest realm of Astronomical study, that of the Stars and Nebulæ, the Zodiacal Light may, in due course of time, prove to be no more a stumblingstone, but a stepping-stone of the utmost help and value in the path by which knowledge grows from more to more.'

E. LEDGER.

IN the kingdom of Ametros rules Phusis, the Queen of the Immortals; at the birth of Chronos her reign began, and not till Chronos dies shall her empire end. She is Queen alone, supreme; the Immortals love her and men too have loved and worshipped at her shrine; but love and worship move her not, she claims obedience: all living things obey her will and all that have lived in the past have done her bidding; things without life also, the rocks and the earth and the sea, keep her laws: all worlds likewise, the moons and the far off stars, continually obey the commands of Phusis and acknowledge her as Queen.

Through all her realm pass Baros and Therme and many more of the Immortals, and as they pass they carry out her will; but they do not understand it; why she bids them do the things they do they mostly neither know nor care, they only do her bidding and none may interfere.

From the birth of Chronos until now the laws of her kingdom have known no change; nowhere are they written and Phusis only knows them all; yet does she never change them nor let others, Mortal or Immortal, change them either.

Boulesis even, that seems sometimes to control or to direct some of the servants of Phusis and to be changeful and inconstant often

The Story of the Golden Mist is the story of the Nebular Hypothesis. The reference to Selas writing the story 'line after line,' is to Spectrum Analysis. The transformations of the Mist' trace the changes in a Nebula till it becomes such a system as that of the Sun and planets. Selene placed in front of Helios describes a solar eclipse, and the daily news of the crown of faint radiance' anticipates seeing and photographing the solar corona at other times than during eclipses, a feat which has not yet been accomplished. The traces of Therme's vigour in Selene are lunar craters.