Knoxville journal. [volume] (Knoxville, Iowa) 1874-1986, 1875-02-04
The Observations at Cairo.


The special correspondent of the Lon
don Times who accompanied the expedl-
ton 10 witness the recent transit of
Venus at Cairo writes as follows:
"The sites chosen at Cairo and The es
were on the east of the Nile and mum
dated ground, so as to keep the probable
ing with the observations of che phe-
nomena at sunrise on the 9th of Decem-
Der. For four days previous to the
transit morning the weather was bad
On three of them there was dense mist
everywhere, and on the other day
mist was in the plain in which the Mo-
kattam hills stood like islands. During
the night preceding the transit there
were occasional breaks in the clouds,
and in the morning it was plain they
were opening, but it was question If
they would do so soon enough to show
the suns disc plainly before Venus had
crossed it. Apparently some English
visitors thought the chance worth con-
siderable effort, for among the shadows
of the Mokattam hills might be seen
parties coming up with telescopes and
tripod rests. BY sunrise were seen the
various observers with their telescopes
pointed to the eastern horizon, which
was covered with banks of cloud
=" A small break in the clouds showed
Venus distinctly TO the most of the OBJ
servers, though it was mere glimpse.
The strictest order had been given not to
speak for fear of interfering with the
counting time of the observers. Another
longer break enabled Venus to be
brought into the field of all the tele-
scopes and micrometric measures to be
commenced. Alternately hid in cloud
and visible for short period Venus con-
tinued her course. The sky was now
clear all over the west up to the zenith,
and it was obvious that it was race as
to whether the clouds or Venus should
first be clear of the sun. Happily, after
one long, anxious period of obscurity,
the sun was seen to be passing into the
clear sky, and there was still a distinct,
unbroken thread of light between Venus
and the suns limb, and the critical phase
of contact was observed. The instant
when the black drop assumed the same
depth of blackness as the body of
the planet had been the phase
adopted as most truly showing
that the limbs of Venus and
the sun conceded. The times regularly
recorded when reduced lay within about
three seconds of each other. In the
largest telescope, the Lee, as might be
expected, contact was seen the latest.
As none of the observers spoke at the
time to each other, and as the times,
written down by different clocks or chro-
nometers, had to be brought TO the same
terms for comparison, there could have
been no unconscious influence exercised
by one observer on another, and the agree
ment within three seconds OF large and
small telescopes must be considered
good. The general appearance of the
phases is reported nearly the same as
that of the Greenwich model. The black
drop was considered less long and dis
tinct, but the very close resemblance
made the observers feel at home with
the work and prevented nervousness.
The approximate time of contact was
nearly that predicted. To the exact
time the observers will not commit them
selves till the stars of the same day are
worked out and the clock errors made
certain