But even if the fixed stars were meant, the objection would be no longer tenable. It rests on certain estimates as to the supposed distances of the fixed stars and star clusters, which were formed by the late Sir W. Herschel from what he designated the "space- penetrating power" of his telescopes. Starting with the assumption that the stars were of tolerably uniform size and brilliancy, and that the difference in apparent brightness was the result, and therefore a measure of their distances, he proceeded to apply the same process to the star clusters, which, even in a fair telescope, present only the appearance of faint nebulous spots of light, but are resolved into clusters of stars by more powerful instruments. In many cases, he found that a certain proportion existed between the telescopic power by which a cluster was first rendered visible, and that required for its resolution, and by this means he formed what he considered a probable estimate of its distance. Other clusters there were which only became visible in his most powerful telescopes, and which, therefore, he could never succeed in resolving. These he placed at a still greater distance, and from this estimate he deduced the conclusion that their light must have been in some cases as much as 60,000 years in reaching the earth. But the whole foundation on which this long chain of inference rested has now been shown to be evanescent. In the first place many of his irresolvable nebulae have been proved by the spectroscope to be true nebulae--masses of luminous gas, and not star clusters at all; and, in the next place, the actual distances of a few of the fixed stars have been approximately ascertained, and it is proved beyond all doubt that the different degree of brightness exhibited by different stars is no test at all of their distance. Of all the stars in our hemisphere whose distance has thus been measured, the nearest to us is one which can only just be discerned by a practised eye on a favourable night, 61 Cygni, whilst the most brilliant star visible in England, Sirius, is at a considerably greater distance. The most competent judges estimate the magnitude of Sirius as about one thousand times that of the sun [Footnote: Mr. Proctor in Good Words, February, 1872.]. In addition to this, many stars of very different magnitudes are found to be related to each other in such a way as to show that they are in actual, and not merely in optical proximity. The clusters which were formerly supposed to consist of large stars at enormous distances from us, are now, upon very solid grounds, believed to be formed of much smaller stars, at much more moderate distances, so that it is very improbable that there is any object visible in the heavens whose light has taken so much as 6000 years, instead of 60,000 years to reach us. THE NEBULAR THEORY.