Dec. 14, 1882 | 
NAP RE 
157 
was able to make his usual spectroscopic observations on 
the limb of the sun, and he saw that on that part of the 
limb at which the first contact would take place, the 
chromosphere was regular, but composed of very active 
flames, and two protuberances bounded the section (¢7az/) 
of the chromosphere, on which the planet might be 
looked for before the first external contact. In fact, 
Signor Tacchini, at 2h. 24m. 33°8s. mean Roman time, 
saw the edge of the planet on the sharp points of the 
chromospheric planes He continued to see very clearly 
the planet advance towards the base of the chromosphere, 
and he observed the first external contact at 2h. 48m. 
5443s. Afterwar!s he watched the complete reappear- 
ance of the chromosphere, and then he noted the first 
internal contact at 3h. 9m. 34'79s. The image of the 
chromosphere was always very well preserved, and the 
size of the planet projected upon it always very clear. 
Prof. Milloseisch observed the contacts at the follow- 
ing times :—First external contact, 2h. 49m. 48"14s. ; first 
internal contact, 3h. 9m. 29°34s., for the moment of the 
appearance of the black drop, and 3h. tom. 10'14s. for 
the moment of the disappearance of the drop. Between 
the times noted by the two observers for the first con- 
tact, the difference amounts to 94 seconds, which clearly 
proves the great advantages of making use of the spectro- 
scope. Shortly after the first contact, Prof. Milloseisch 
perceived for the first time the presence of the planet's 
atmosphere, verified by Signor Tacchini and his assistant. 
Signor Tacchini even observed in the spectroscope the 
phenomenon of absorption by that atmosphere, as in 
Bengal in 1874, and even at Palermo something of the 
same kind has been seen. MM. Tacchini and Milloseisch 
did not see the entire planet before the first contact. 
The atmosphere of the planet was more active near the 
edge of the sun. Prof. Milloseisch estimates the height 
of the atmosphere of Venus at one-fourteenth of the 
planet’s diameter. Signor Tacchini found the diameter 
of Venus to be equal to 67°25. 
I HAD the advantage of seeing here yesterday the 
transit of Venus, under exceptionally favourable circum- 
stances, by means of a very simple and ingenious appa- 
ratus fitted up by my cousin, Mr. J. Campbell, of Islay. 
The image of the sun was thrown from a small telescope, 
properly focussed, upon a large sheet of cardboard paper, 
ina dark room. The size of this solar image was a little 
more than two feet in diameter. Upon this image the solar 
spots and some brilliant “‘facule” were very distinctly 
visible. As the time approached, Mr. Campbell expected 
that we might see the planet whilst yet some little distance 
from the illuminated edge of the sun, owing to the atmo- 
sphere of the planet catching and reflecting some solar 
light before the apparent contact. I believe Mr. Camp- 
bell had seen this on the occasion of the transit, in the 
clearer atmosphere of Japan. Here, none of the party 
could detect the planet before its disc began to impinge 
on the edge of the sun. But when the planet’s disc had 
advanced about one quarter of its own diameter upon the 
solar image, then a faintly luminous ring was distinctly 
seen defining the rest of the planet’s disc, in the dark- 
ness out of which it was moving. For some time I was 
incredulous as to this appearance ; but before one half of 
the planet’s disc had crossed the illuminated edge of the 
sun, the luminosity of the other side of that disc was too 
distinct to be doubted, and the appearance was very 
striking and beautiful- I may mention that the size of 
the planet’s disc was, as nearly as possible, seven-tenths 
of aninch. The time of contact was exactly 2.28 p.m. 
Cannes, December 7 ARGYLL 
AT th. 48m. 28s. Dunsink mean time, I first saw the 
sun through an opening in the clouds. Venus was at 
once seen (in the finder of three inches aperture attached 
to the south equatorial), and was estimated to be about 
one-third of the way on the sun. But the snow and 
clouds again intervening, there was nothing more to be 
seen until 2h, 37m. 19s., when I was enabled to commence 
a series of micrometric measures with the large instru- 
ment. I used a polarising eye-piece and a power of 177 
with the Piston and Martin filar micrometer. The limb 
of the sun was boiling furiously, and Venus was often of 
any Shape but a circular disk. The measures were conse- 
quently by no means easy. I set one wire tangentiaily 
on the sun’s limb, and the other on that of Venus. Alto- 
gether I was able to make sixteen of such sets, nine being 
made with the limb of Venus nearest the sun’s centre 
and the remainder with the other limb. The following 
are the results :— 
Dunsink mean time. Far limb of Venus. Near limb of Venus. 
bss Sy 0 it 
2 37 19 171 as cea — 
39 24 177 os te 3S 
40 42 185 — cae — 
2 18 187 site sha -- 
44 13 I9I te nts — 
45 20 190 BA ae _ 
46 22 198 tt me — 
48 17 si 0 196 es a3 — 
2 16 oe 8s _— 142 
54 16 is tH — 149 
55 36 ni os 215 — 
58 17 = See _— 161 
59 30 sic Ao — 164 
30 46 ee AG — 161 
I 41 ae Aa — 164. 
2 51 tee ee — 170 
These results have not been corrected for refraction. 
I conclude from the mean of the first series that at 2h. 
43m. 30s. the far limb of Venus was 188” from the limb 
of the sun, while at 3h. om os. I conclude from the second 
series that the near limb of Venus was 162” from the 
sun. By a projection of the results it is easy to see that 
the diameter of Venus must have been 64”. 
My assistant, Mr. Rambant, was observing with the 
small equatorial, which is 78 metres from where I was 
observing. He reports as follows: ‘At th. 45m. the 
clouds, which up to that time had obscured the sun, 
cleared away, and I saw the planet with about one-half 
of its disc projected on that of the sun, but a snow-shower 
coming on almost immediately, I was unable to perceive 
any trace of light rouud Venus, or even to follow its out- 
line beyond the limb of the sun. By the time the snow 
cleared away the internal contact was passed, and Venus 
appeared at about twice of its own diameter from the 
sun’s limb ; the sun’s light appeared of great brightness 
right up to the dark disc of the planet except at the 
northern limb, where I suspected a dark brown fringe, 
but the boiling was such that I could not be certain of 
this. R. S. BALL, 
Astronomer Royal of Ireland 
Dunsink Observatory, Dublin 
THE transit of Venus was well seen at this observatory 
owing to the unusually favourable state of the weather. 
I observed it in the Markree refractor with an aperture 
reduced to five inches. I did not meet with any diffi- 
culties and saw no “black drop,’’ perhaps because I had 
focussed the eyepiece on double stars the night before. 
Owing to the boiling of the sun’s edge, I did not see 
Venus till 1h. 27m. 38s., external contact having taken 
place previous to this. I then measured the distance 
between the cusps micrometrically, and from a provisional 
reduction of these observations it appears that Venus was 
bisected at 1h. 37m. 53s. The internal contact was first 
noticed at th. 46m. 4os., when a fine line of light appeared 
at the outer edge of Venus. At th. 47m. 58s. the cusps 
