, 1882-12-02

officers, When the day OF observation
arrived the four observers prepared them
selves and agreed that neither by word or
signswould they communicate to each Other
the moment of contact, but each would de-
eide it for himself as independently OF the
rest as possible. The result was very
satisfactory when we take into COnsldefa-
ton the Indifferent character OF the IN
strnments used and the want of experience
in the observation.
Chappe, who, as already said, observed
in California, had arranged an exceeding.
" good observatory in q barn, ana had
determined the rate of his pendulum aS
well as the latitude and longitude OF the
Mace with GREAT eractness. The weather
was very favourable and all the conditions
we're present for securinga a good observation.
At the first inner contact Of Venus Chappe
observed the phenomenon OF "Ia goutc
noire," which he had already noticed III
1761. In regard to it he writes "1he
edge of Venus was extended as if attract
ed by the suns edge. | did not note the
time, when it began to ertend as could not
doubt that the black band which was thus
formed was Il portion Of Venus, and |
therefore observed only that moment when
It disappeared. The black band was IA
Their less lark than the rest ofNenuS. |
believe it to be the same phenomenon
which | observed at TObolSk IN lI6l'"
At the second inner contact both the sun
and Venus appeared to be in waving mo.
ton on account Of atmospheric dlsturban-
ces, and the observation was thus render
ed very difficult: this time Venus Was
heightened ont more than IN the morning,
appearing suddenly to eGtend itself to the
SUMS edge. During the Whole transit
Nhappe took at tiGed mOmentS OF time the
differences in right asCensiOni and deCllna-
ton of the circumference OF the sun ana
the planet: be also took the least distance
between the two centres. The success
which attended Chappe in his observation
was dearly paid for, the whole expedition
being attacked three days later by n dan
gerous epidemic. Chappe himeelf was St.
verely attacked, but would nevertheless
have come safely over his sickness II he had
not during his cOnvalesccnce Impru-
IDENTIFY exposed himself by observing
an eclipse of the Don on the night OF
June the 18th, whenhe got Il relapse,
and died on the list Of August.
Three days before his death he said
TO his friends II know that it is all
over, and that | have but a short
time to live, but ! have fulfilled my
mission and | die content"
The phenomenon of the black
Land was also observed by He'll at
Vard0huus and DR.. Benz ut Aew.
At Greenwich Ma~kelyn found IA diff
ference of 50 seconds, and Ilornsby
62'seconds between The two phases
of the inner contact. At those stn-
tons where only one of the phases
was noted we find that the moments
were far from b. ing Identical for all
the observers at a station. Thus the
astronomers at the Palace "$t. iiu-
bert" made a difference OF 36 seconds,
at Brest 30 seconds and 50 on. Thus
we see what uncertainty pre- vailed
as to judging of the moments of con
tact.
Over two hundred memoirs were
sent in to the Academy Of sciences
on the size of the parallax, deduced
from certain groups OF observations,
and although the results of these dill
fered much among each other yet
there was q great advance on the re-
suit of 1851. The value of the par
allax now varied between 8".5 and
SO, the former being the result OBJ
tainedby LaIande, the latter by Pin
gre. These two French astronomers