Among the latter is the character of the changes from
year to year, which the great length of this series of observations
brings well to light. It is found that from year to year the mean
temperature of the surface for the year, varying by three or four
degrees of Fahrenheit, follows in its changes the mean temperature of
the atmosphere for the year, and that the changes of annual
temperature are propagated downwards, retarded in phase and
diminishing in amount of change, in the same manner (though probably
not following the same law) as the season changes. The inference from
this is, that changes of temperature come entirely from the exterior
and in no discoverable degree from the interior; an inference which
may be important in regard both to solar action and to geology.
--Referring to the Transit of Venus observations: In the
astronomical part of the reductions, there has been great labour and
difficulty in the determination of local sidereal times; some books of
observations required extensive transcription; some instrumental
errors are still uncertain; the latter determinations have perplexed
us so much that we are inclined to believe that, in spite of the great
facilities of reduction given by the transit instrument, it would be
better to rely on the altazimuth for time-determinations.
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