Page:Across the Zodiac (Volume 1).djvu/64

 distance from the Earth, which appeared to be about 120 terrestrial radii. The light of the halo was of course very much narrower than when I first observed it, and its scintillations or coruscations no longer distinctly visible. The Moon presented an exquisitely fine thread of light, but no new object of interest on the very small portion of her daylight hemisphere turned towards me. Mars was somewhat difficult to observe, being too near what may be called my zenith. But the markings were far more distinct than they appear, with greater magnifying powers than I employed, upon the Earth. In truth, I should say that the various disadvantages due to the atmosphere deprive the astronomer of at least one-half of the available light-collecting power of his telescope, and consequently of the defining power of the eye-piece; that with a 200 glass he sees 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