NATURE 
| Mov. 30, 1882 
110 
Distance a = 0°66 I 
as = 1°70 > November 3. 
” c= 084 
Distance a = 0°74 } 
3 = 1°66 » November 6. 
rr ¢ = 1°03 \ 
Assuming 0°1705 and 0'1714 to be log. A on those days 
respectively, the distance a would be about 4000 miles, 
the distance 4 about 10000 miles, and the distance c about 
5500 miles. 
It would not be surprising, judging from the history of 
this comet, if another condensation developed in the por- 
tion of the coma nearest the sun, thus forming four 
nucleuses. W. T. SAMPSON, 
Commander U.S.N. 
Naval Observatory, Washington, November 11 
Since my first communication, with sketch of the comet, 
on October 21, which appeared in NATURE, vol. xxvi. p. 
622, I have had good views on 21 out of 31 days. The 
fine weather and clear atmosphere of this place give 
exceptional facilities for the continued and frequent ob- 
servations which are needed to obtain a knowledge of so 
anomalous and surprising an object. Some windows of 
my villa command an extensive sky and sea view (includ- 
ing at times the mountains of Corsica, 120 mules distant), 
and from my tbedroom—sometimes even from my bed—I 
have been able to watch the comet with ease for from a 
quarter of an hour to an hour, on each of those twenty- 
one days ; using only a good field binocular in occasional 
aid of a strong natural sight. I have more powerful 
telescopes, but for this object they give no help; and I 
am not astronomer enough to avail myself of other 
instruments. 
The comet was seen in all its brightness on October 
20, 21, 23, and 24, with its nucleus like a star of first 
magnitude, but elongated and nebulous—its tail beginning 
with slender stem, slightly curved, with downward con- | strikes one as showing how much more it has lost in 
vexity, and gradually expanding to its extremity, the 
diameter of which was about five times that of the head. 
The lower, slightly convex margin, was brighter, and 
more defined ; but a strong nedulous light pervaded the 
length and breadth of the tail, shaded along the upper 
margin in gradually diminishing haze. 
an elongated crescent, the lower or eastern horn of which 
was longer than the other. 
in faint lines, hardly perceptible, a few degrees further 
(as noticed by your correspondent, Mr. Larden). No such 
prolongation could be seen from the hollow of the cres- 
cent, which terminated by a narrow fringe of diminishing 
light, beyond which was an oval patch of shade, oéviously 
darker than any other portion of the visible sky. This 
appeared to me nothing else than a shadow projected by 
the comet on the space beyond the end of its tail. I 
cannot admit the correctness of Major Herschel’s szs- 
pictons, “that this impression was produced by contrast 
only” (NATURE, vol. xxvil. p. 4). The still greater 
contrast between the brightness of the lower margin and 
the adjoining sky produced no such shade there a¢ that 
time; \ater I shall allude to such a shade appearing there 
also. 
experience in landscape painting has given me some skill 
in appreciating lights and shades. 
the difficulty of physically explaining the existence of 
light and shadow in the vacuity of space, but this is a 
question of pure observation, to which I invite further 
attention. 
Cheltenham, and Mr. Cecil of Bournemouth, describe 
“a black rift in the sky,” and “a strong apparent 
shadow”’ behind the comet—seemingly in confirmation 
of my observation. 
When the comet was next seen, after an interval of 
bad weather, on the 2gth it had lost in dimensions, but 
still more in brightness, and its form was changed. The 
The tail ended in | 
Both horns were prolonged | 
The ultra-caudal patch was obviously darker than | 
any other spot of the sky : so it appeared to me, and my | 
1 am quite aware of | 
Two of your correspondents, Mr. Larden of | 
upper margin from the head upwards had expanded and 
become more feathery ; so had the end of the tail, which 
had lost its crescentic form; the shadow beyond had 
quite disappeared, and was replaced by an ill-defined 
luminosity, losing itself in the darkness of the sky. The 
lower margin of the tail had lost less of its brightness and 
‘definition ; and now if there was a shadow anywhere, it 
was along this edge, down even to the head of the comet ; 
but the shade was much less marked than had been that 
beyond the tail, and I might have ascribed it to contrast 
but that it was not present when this margin was brighter 
and the contrast greater. This shadow is noticed by Mr. 
Cecil in NATURE, vol. xxvii. p. 52. 
The comet was well seen on October 30 and 31, and 
November 2, 3, 4, 6, and 7, gradually diminishing in 
brightness and in the definition of its outline, its light 
being now further paled by moonlight. So faint was it 
that I am not surprised at Major Herschel’s description® 
of its non-appearance in the London sky of November 
5; but I cannot help “ suspecting ” that this was due not 
to moonlight only (as the testimony of others proves), but 
also to the gas-lit haze of the London atmosphere, which 
from fiftv years’ experience I know to be, at its clearest, 
quite sufficient to mask a faded comet, even although the 
brighter light of stars may still remain visible. On the 
8th the comet was seen before moonrise, more distinct, 
although pale and hazy in outline; lower margin still the 
brightest, with a slight attendant shade. It was seen 
every day (except the 13th, r4th, and 15th) until the 22nd, 
with little other changes than that it was gradually be- 
coming fainter, although still a conspicuous object-in the 
dark sky from 2 to 5.30a.m. On the 21st I made a 
careful portrait of it in oils, with its attendant stars, by 
the side of one that I had painted from the sketch taken 
October 21, when it was in its glory. The alteration 
which has taken place in the month is such that it now 
seems the mere ghost of its former self. The comparison 
brightness and compactness, than in length and breadth. 
Is not this in exact conformity with what has been ascer- 
tained (see NATURE, vol. xxvii. p. 58) that the comet has 
been receding more rapidly from the sun than from the 
earth. C. J. B. WILLIAMS 
Cannes, November 23 
THE APPROACHING ECLIPSE OF MAY 6, 1883* 
(C2 sixth of May next year will witness, in the distant 
regions of Oceania, one of the rarest and most 
important astronomical phenomera of the century, viz. a 
total eclipse of the sun, which, owing to the respective 
| positions, but rarely realised, of the sun and the moon, 
will have a duration quite extraordinary. 
Now, in the present state of science, when the most 
important questions as to the constitution of the sun and 
that of the unexplored spaces near him, and the existence 
| of those hypothetical planets which Le Verrier’s analysis 
indicated within the orbit of Mercury, are still pending, a 
phenomenon which presents to us, for long minutes, all 
those regions, with the sun’s dazzling brilliancy with- 
drawn, and renders them accessible to observation, is one 
of the first order. 
We shall presently examine the conditions under which 
this rare solar occultation will be produced ; let us first 
see what is the state of the questions which have to be 
considered on this occasion. One of the most important 
is thatregarding the constitution of the space immediately 
bordering on the envelopes of the sun at present known. 
The great Asiatic eclipse of 1868, came wonder- 
fully @ propos, both by its lung duration and by the 
maturity of the problems that hac to be attacked, enabled 
us in some sort to tear the veil which hid from us the 
t Report to the Bureau des Longitudes, by a Commissirn cors sting of 
MM. Fizeau, Admiral Clou¢, Lewy, and Janssen (reporter). 
