150 
NATURE 
| Dec. 14, 1882 
I have not Darwin’s book at hand while I write, but does he 
not mention the Germander Speedwell ? 
Bedford, December 9 ARTHUR RANSOM 
Shadows after Sunset 
FIVE years ago my attention was attracted to the phenomenon 
now under discussion. I was then at San Fernando, and could 
perceive almost every evening the rosy and blue or black and 
white rays converging to a point apparently below the horizon. 
I was able to trace the rays from west to east many times, and 
frequently also to trace the black or blue spaces to visible pro- 
minences in the cumuli in the western horizon, to whose shadows 
there is no doubt the rays were due, as they swept the sky with 
such a rapidity ; and they were so persistently traceable to the 
bright bordered cumuli, that even though there were any hills in 
the direction of theJsetting sun (which there were not), the phe- 
nomenon could not be attributed to them. Besides, I have 
observed it when off the coast of Portugal, which leaves the 
hill shadows out of the question, as the observations were made 
in the (two consecutive) evenings. Though the sky is too cloudy 
in this part of Spain, by lookiny at the right place at the right 
time I have been able to see it many times. The mock sun 
described by Mr. Rand Capron in the last number of NATURE 
(p. 102) was seen once by me, but the phenomenon was but 
little conspicuous. The rays are seldom equidistant. 
Naval School, Ferrol, Spain, December 5 Pror, DiER 
Complementary Colours 
IN connection with recent correspondence in NATURE it may 
be worthy of remark that I have often noticed the appearance of 
strong complementary colours in water from contrast-effects, in 
the case of a wave, breaking on the shore. If the water is pro- 
perly illuminated so as to be of a decidedly green tinge, the crest 
of the wave often appears of a delicate pink, and this even in 
strong sunlight. The purplish bue of cloud-shadows on the 
ocean is also a familiar example of the phenomenon under dis- 
cussion, CuHas. R. Cross 
Mass, Institute of Technology, Boston, November 23 
An Extraordinary Lunar Halo 
I PURCHASED a copy of NaTuRE of November 30 in the 
hopes of finding some account of a lunar halo observed by myself 
and several friends on Saturday night, November 18, about 10.30, 
Instead of which I find that Mr. Barkas has sent you an account 
of one seen by him on the following Monday. His description 
tallies almost exactly with the one seen by me, with the exception 
of date and hour, Can any of your readers give any information 
respecting them ? S. A. Goop 
751, Wandsworth Road, S.W. 
“Lepidoptera of Ceylon” 
ALLOw us to correct a slight error in the address of the Presi- 
dent of the Royal Society, as reported in NaTuRE last week. 
He speaks of the ‘‘ completion” of the “ Lepidoptera of Ceylon” 
having been presented to the Library, whereas it is only the first 
of the three volumes of that work which is as yet complete, 
Part vi., being the second part of the second volume, will be 
ready next week, and the succeeding parts will follow in due 
course. The error is not very important, but might mislead 
subscribers and others interested in the work, 
L. REEVE AND Co. 
5, Henrietta Street, Covent Garden, London, W.C., 
December 11 
THE COMET 
V HEN the comet was first seen on September 16 at 22h. 
45m. its appearance was most symmetrical, in colour 
a most intense white. The sketch shows the appearance 
on such a scale that the nucleus would havea diameter of 
about 45", by a comparison made at the time with a sun- 
spot, the exact size of which has since been kindly fur- 
nished by the Astronomer Royal from the Greenwich 
phctographs of the sun. The direction of the comet was 
to the centre of the sun, as far as could be estimated. On 
p. 81 of this volume there is a diagram of the sun and the 
comet ; the size of the comet as there given compared 
with the sun is about as it appeared ; and if one imagines 
the sketch I give, reduced to the length of the sign for 
the comet on the diagram, and placed some two diameters 
of the sun to the south-west and radial, he will have a 
good idea of the appearance on the morning of Sep- 
tember 17. 
The general appearance of the comet has been so fully 
described that I will confine myself to some points that I 
have observed with the three-foot reflector, which I did 
not get to bear, however, till October 29 at 16h. 4om. 
September 16, 22h. 45m. 
Although the moon was very bright the comet was well 
seen, the nucleus appearing as an oval bright spot fading 
into the head gradually (this is called the nucleus in my 
note-book, but subsequent observations show it ought to 
be called the bright part of the head). The most notice- 
able feature of this morning’s observation is the peculiar 
termination to the head ; at the n.f. side of head (see 
sketch for October 30), there was noted an absence of light, 
while the extension on the south side was particularly 
noticed, there may have been some extension on the 
corresponding north side, but I have not recorded Tbs 
so the appearance would then be similar to that in sketch 
No. 2 (NATURE, vol. xxvii. p. 109). This oblique termi- 
October 30, 16h, 50m. 
nation appears in all my sketches made at the telescope. 
The length of this nucleus or bright part of head was 
measured as 55”. An absence of stripes in the tail was 
particularly noticed, if there was a difference the south 
side was a little the brightest. 
On this morning the brightness of the moonlight had a 
marked effect on the visibility of the broader part of the 
tail, so much so that it was easier to trace it in the sky 
with the naked eye, than with either a binocular, a 3-inch 
achromatic, or a 3-foot reflector. 
The following morning, October 30, 16h. 50m., the 
appearance of the comet was so altered that either a 
