less than a power of 100 reveals to an eye situated in space; though, from the nature of the lens through which I looked, I cannot speak with certainty upon this point.  With a magnifying power of 300 the polar spots of Mars were distinctly visible and perfectly defined.  They were, I thought, less white than they appeared from the Earth, but their colour was notably different from that of the planet’s general surface, differing almost as widely from the orange hue of what I supposed to be land as from the greyish blue of the water.  The orange was, I thought, deeper than it appears through a telescope of similar power on Earth.  The seas were distinctly grey rather than blue, especially when, by covering the greater part of the field, I contrived for a moment to observe a sea alone, thus eliminating the effect of contrast.  The bands of Jupiter in their turn were more notably distinct; their variety of colour as well as the contrast of light and shade much more definite, and their irregularities more unmistakable.  A satellite was approaching the disc, and this afforded me an opportunity of realising with especial clearness the difference between observation through seventy or a hundred miles of terrestrial atmosphere outside the object glass and observation in space.  The two discs were perfectly rounded and separately discernible until they touched.  Moreover, I was able to distinguish upon one of the darker bands the disc of the satellite itself, while upon a lighter band its round black shadow was at the same time perfectly defined.  This wonderfully clear presentation of one of the most interesting of astronomical phenomena so absorbed my attention that I watched the satellite and shadow during their whole course, though the former, passing after a time on to a light band, became comparatively indistinct.  The moment, however, that the outer edge passed off the disc of Jupiter, its outline became perfectly visible against the black background of sky.  What was still more novel was the occultation for some little time of a star, apparently of the tenth magnitude, not by the planet but by the satellite, almost immediately after it passed off the disc of the former.  Whether the star actually disappeared at once, as if instantaneously extinguished, or whether, as I thought at the moment, it remained for some tenth of a second partially visible, as if refracted by an atmosphere belonging to the satellite, I will not venture to say.  The bands and rings of Saturn, the division between the two latter, and the seven satellites, were also perfectly visible, with a distinctness that a much greater magnifying power would hardly have attained under terrestrial conditions.  I was perplexed by two peculiarities, not, so far as I know, hitherto [5] mentioned by astronomers.  The circumference did not appear to present an even curvature.