point. Now, within this spot, which shows no stars to the naked eye, a telescope of moderate power reveals a multitude of brilliant stars, the brightest of which are of about the seventh magnitude. Around these there still appears a milky unresolved light. If a telescope of higher power be applied, more stars are seen, and around these there still remains a nebulous light. Increase power until the whole field blazes with almost unbearable light, yet still there remains an unresolved background. The illustrious Herschel,' says Professor Nichol, 'penetrated, on one occasion, into this spot, until he found himself among depths, whose light could not have reached him in much less than 4,000 years; no marvel that he withdrew from the pursuit, conceiving that such abysses must be endless.' It is precisely this view that I wish to controvert. And I think it is no difficult matter to show at least a probability against the supposition that the milky light in the spot is removed at a vast distance behind the stars of the seventh magnitude seen in the same field.

The supposition amounts, in fact, to the highly improbable view that we are looking here at a range of stars extending in a cylindrical stratum directly from the eye-a stratum whose section is so very minute in comparison with its breadth, that, whereas the whole field within which the spot is included is but small, the distance separating the nearest parts of the group from the farthest, is equivalent to the immense distance supposed to separate the sphere of seventh magnitude stars from the extreme limits of our galaxy. And the great improbability of this view is yet further increased, when it is observed that within this spot there is to be seen a very marked tendency to the formation of minor streams, around which the milky light seems to cling. It seems, therefore, wholly improbable that the cluster really has that indefinite longitudinal extension suggested by Professor Nichol. In fact, it becomes practically certain that the milky

light comes from orbs really smaller than the seventh magnitude stars in the same field, and clustering round these stars in reality as well as in appearance.

The observations applied to this spot may be extended to all clusters of globular form; and where a cluster is not globular in form, but exhibits, on examination, either (1) any tendency within its bounds to stream-formation, or (2) a uniform increase in density as we proceed from any part of the circumference towards the centre, it appears wholly inconceivable that the apparent cluster is, not really a cluster, but a long range of stars extending to an enormous distance directly from the eye of the observer. When, in such a case, many stars of the higher magnitudes appear within the cluster, we seem compelled to admit the probability that they belong to it; and, in any case, we cannot assign to the farthest parts of the cluster a distance greatly exceeding (proportionally) that of the nearest parts.

Of a like character is the evidence afforded by narrow streams and necks within the galaxy itself. If we consider the convolutions over Scorpio, it will seem highly improbable that in each of these we see, not a real convolution or stream, but the edge of a roll of stars. For instance, if a spiral roll of paper be viewed from any point taken at random, the chances are thousands to one against its appearing as a spiral curve, and of course the chance against several such rolls so appearing is very much greater. The fact that we are assumed to be not very far from the supposed mean plane of the Milky Way would partly remove the difficulty here considered, if it were not that the thickness and extent of the stratum, as compared with the distances of the lucid stars, must necessarily be supposed very great, on the assumption of any approach to uniformity of distribution.

Evidence pointing the same way is afforded by circular apertures in the galaxy, or indeed by apertures of other forms,

since a moment's inspection of figs. 1 and 2 will show the improbability of any tunnelling (so to speak) through the star stratum, being so situate as to be discernible from the centre. Another peculiarity of these cavities is also noticeable; whereas on the borders of every one there are many lucid stars, or in some cases two or three very bright stars, within the cavity there is a marked paucity of stars. This phenomenon seems to indicate a much closer connection between the brighter stars, and the milky light beyond, than is supposed on the stratum theory. One can hardly conceive the phenomenon to be wholly accidental.

There are some other points on which I would fain dwell, but space will not permit me. I may, perhaps, on another occasion, return to the consideration of the subject. For the present, I will merely note that there are peculiarities in the distribution of red double, and multiple stars, in the position in which temporary stars have made their appearance, and in the distribution of nebula, which seem very worthy of notice.

One point, however, immediately connected with my subject, remains to be mentioned. I have traced streams of stars more conspicuous than those forming the Milky Way. We have also evidence of streams of light yet more delicate and evanescent than the light of our galaxy. In Sir John Herschel's great work on the southern skies, he notes the frequent recurrence of an exceedingly delicate and uniform dotting, or stippling of the field of view by points of light too small to admit of any one being steadily or fully examined, and too numerous for counting, were it possible so to view them.' In thirty-seven places he detected this remarkable and significant phenomenon; a phenomenon so faint that he says, The idea of illusion has continually arisen subsequently;' an idea well befitting the modesty of the philosophic observer, but which those who appreciate Sir John Herschel's skill as an observer will be very unwilling

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to accept. As Professor Nichol remarks, 'It is enough to read from Herschel's note-book-"I feel satisfied the stippling is no illusion, for its dark mottling moves with the stars as I move the tube to and fro "-to feel convinced that the phenomenon is real.' Now, a remarkable fact connected with those observations is, that when Sir J. Herschel marked down in a star-chart the places in which he had detected this nebulous appearance, he found that, with the exception of three, which appeared outlying and disconnected, they formed several distinct but continuous streams.'

From the Intellectual Observer for August 1867.

STAR STREAMS AND STAR SPRAYS.

THE stellar heavens present us with a problem of vast difficulty-the problem of determining the laws according to which those myriads of orbs which the unaided eyes can see, or which the telescope reveals, are distributed throughout space. We can determine the laws of stellar distribution so far as they relate to the imaginary concave of the heavens. We could form a globe upon which millions of stars might be indicated; or better, we might mark these millions of stars upon the interior surface of a hollow globe; and thus, so far as the apparent laws of stellar arrangement are concerned, we might actually render the eye cognisant of all which even the most powerful telescopes can reveal. But when this had been accomplished, we should have made but a short step towards the determination of the manner according to which the stars are distributed throughout space. We should have placed all the stars which the telescope reveals upon a spherical surface, whereas we know that they lie in reality on no such surface, but some at distances much vaster than the distances which separate us from others. We know that if we have to deal with a sphere of stars at all it is a sphere full of stars, and not a spherical surface covered with stars, that we have to consider. But, in truth, we know that the space containing all the stars revealed by powerful telescopes may not even approach the form of a sphere; and that within that space the stars may be distributed in the most irregular manner-here crowded most

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