The definition in both planes was then found to be perfect.--The
number of small planets has now become so great, and the interest of
establishing the elements of all their orbits so small,--while at the
same time the light of all those lately discovered is very faint, and
the difficulty and doubt of observation greatly increased,--that I
have begun to think seriously of limiting future observations to a
small number of these objects.--All observations with the Spectroscope
have been completely reduced; the measures of lines in the spectra of
elements being converted into corresponding wave-lengths, and the
observations of displacement of lines in the spectra of stars being
reduced so as to exhibit the concluded motion in miles per second,
after applying a correction for the earth's motion. Sixteen measures
of the F line in the spectrum of the Moon as compared with hydrogen
give a displacement corresponding to a motion of less than two miles a
second, which seems to shew that the method of comparison now adopted
is free from systematic error; and this is supported by the manner in
which motions of approach and recession are distributed among the
stars examined on each night of observation.
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