[J] Notch plainly on. Estimated a minute late.
[K] Poor contact. Cloudy.
“The observation of the first contact was interfered with by the
clouds. Between the first contact and the second contact the light
shining through Venus’s atmosphere was a fine sight. I should say that
it first appeared to my eye when the planet was a little more than
half way on the sun, and disappeared about a minute before the planet
reached second contact.
“I might, perhaps, introduce here,” said the professor, drawing a
circle upon the blackboard, “the meaning of the terms first contact,
second contact, and so on. Taking this circle to represent the sun,
Venus is a disc which is about one-twenty-first part the diameter of
the sun, and by first contact we simply mean the instant when the
disc Venus, approaching the disc of the sun, touches it at one point
externally. The second contact occurs at the time when the disc of
Venus just touches the sun internally. The third contact Is the instant
when the disc of Venus just touches the disc of the sun internally on
one side, and the fourth contact is the instant when it touches on the
other side.
“The line of light,” the Professor went on, after his explanation,
“marking out the portion of Venus’ disk not on the sun, changed its
appearance considerably while my attention was fixed upon it. I first
saw a faint curved line of light off of the sun, and apparently
marking out the part of Venus’ disk not on the sun, this curved line
being entirely disconnected from the sun. A little later this arc of
light was lengthened to a semicircular thread and touched the edge of
the sun, marking out the complete outline of the part of Venus’ disk
not on the sun. The semicircular gold thread seemed to be an exact
continuation of the dark rim of the planet. Finally this line broadened
at the point where it touched the sun’s rim, or edge, and the summit
of the arc disappeared. The wings of light thus formed were, at their
base, not in the exact continuation of the dark outline of the planet.
I watched for the repetition of these appearances between third and
fourth contacts, but failed to see anything. The sky between the first
and second contacts was much clearer of haze than between the third and
fourth.
“At second contact I saw no indication of the black drop. The tangency
of Venus’ and the sun’s discs was well seen. During the passage of
Venus over the sun’s face I observed her disc with magnifying powers of
48, 95, 165 and 345, but saw no indications of an atmosphere. The disc
of Venus did not appear to be uniform in blackness, but to be spotted
with grayish or whitish matter, reminding one of patches of snow. This
was seen under the different magnifying powers used.
“When Venus neared the third contact a very peculiar phenomenon was
noticed. The preceding edge of Venus was seen to be darker than the
central portion. Later the edge of the planet became of a bluish black
color, and this extended around to the following edge. The phenomena
connected with this were very distinct. When the planet was near
third contact these appearances were not seen longer. Just before
third contact a faint black drop was observed for a short time. It
disappeared very quickly, and third contact was finely seen.
“The fourth contact was interfered with by the haze and clouds, and was
probably called too early.”
The Professor added that he desired to express his acknowledgments
for aid in the matter of timing and in keeping the clockwork of the
telescope in order to the fourth year civil engineers of the School
of Mines. Without their assistance it would have been impossible to
collect the time data which rendered the observations of value. At the
conclusion of his address he was warmly applauded.