| ADOPTED CONTACT TIMES. | ||||||
|---|---|---|---|---|---|---|
| Mean time of Columbia College. | Mean time in Washington. | |||||
| H. | M. | S. | H. | M. | S. | |
| I - - - - | [*]9 | 8 | 50.0 | 8 | 56 | 31.6 |
| II - - - - | 9 | 28 | 45.9 | 9 | 16 | 27.5 |
| III - - - - | 2 | 52 | 13.5 | 2 | 39 | 55.1 |
| IV - - - - | [†]3 | 11 | 52.1 | 2 | 59 | 33.7 |
[*] Notch plainly on. Estimated a minute late.
[†] 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.