At 8h., I employed for the first time the apparatus which I may call
my window telescope, to observe, from a position free from the
difficulties inflicted on terrestrial astronomers by the atmosphere,
all the celestial objects within my survey. As I had anticipated, the
absence of atmospheric disturbance and diffusion of light was of
extreme advantage. In the first place, I ascertained by the barycrite
and the discometer my 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.
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