Academy Newspaper Saturday 22nd May 1875
Transit of Venus.
Detailed reports from the French Transit of Venus
expeditions to St. Paul’s Island and to Peking are given in the Comptes Rendus.
At the former station, the transit occurred in the midst of a tremendous storm,
but, comforted by the statement of the fishermen that the day of the new moon
(which occurred on December 9), was always fine, M. Mouchez made every
preparation, and was rewarded with complete success, the sky clearing just
before the first internal contact, and clouding over again completely half an
hour after egress. Although passing clouds interfered somewhat with the
photography, no fewer than 443 daguerreotypes and 142 collodion negatives were
obtained during the whole transit, and after deducting a certain number of
unsatisfactory plates, there still remain 439 which will be availabe for
measurement.
With regard to the
eye observations M. Mouchez saw a bright ring of light surrounding the part of
the planet outside the sun, which he attributes to the atmosphere of Venus;
and, further, an aureola, which seemed independent of the planet, and behaved
just like a solar atmosphere. It is rather remarkable that while M. Mouchez,
with the large eight-inch telescope, found great difficulty in fixing the time
of internal contact with anything like precision on account of this aureola,
his companion, at the six-inch telescope, saw nothing of It, and made what he
considered to be most accurate observations. M. Mouchez, however, places most
reliance on the micrometer measures and on the photographs.
At Peking the
observers were equally fortunate, though passing clouds caused great anxiety.
Both internal contacts were well observed, a slight ligament being seen with
the six-inch telescope, but no ring of light; while, with the eight-inch,
nothing was seen but a few fringes. Contrary to what was anticipated, the
Chinese received the expedition well, and even marked attention was paid them
by some of the highest officials, while the dowager empresses showed their
interest in the event by asking for a photograph of the phenomenon. The
longitude of the French station was determined within one and a half seconds of
time, and was also carefully connected by triangulation with the American
station under Professor Watson's charge, while a survey of the town of Peking
was made after the transit, the party being detained for two months by ice in
the river.
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