78 
NATURE 
[\ov. 23, 1882 
The Comet 
THANKS to the entire absence of twilight, and to a beautifully 
clear sky, I obtained a splendid view of the comet on November 
14, 15h. 45m. The tail had a length of 30°, and was divided 
into two portions at the extreme end, the northern extremity 
curving very sharply upwards, and separated from the southern 
branch by a semi-circular space. The general form of the tail 
being very similar to the Greek character y, The southern side 
still remained brighter than the northern. The nucleus was 
much more elongated than when I observed it on November 8. 
The two concentrations of light which were very noticeable on 
that date, were not now so conspicuous, being smaller and much 
closer together, so much so, that had the definition been other- 
wise than perfect the division between them could not have been 
seen. As showing the necessity of observing this interesting 
object in the absence of twilight I may mention that by 17h. 45m. 
G.M.T., the apparent length of the tail was reduced to 20°. 
B. J. Hopkins 
79, Marlborough Road, Dalston, E., November 20 
Soda Flames in Coal Fires 
IF a coal-fire be looked into with some attention after a fresh 
supply of coals has nearly ceased to give out its gases, there will 
b2 seen here and therein the hottest parts, and coming out of 
them through crannies and round dark corners, a pale translucent 
yellow flame, which one soon gets to recognise easily. What 
does it consist of ? If looked at through a prism, without any 
slit screen, this flame is at once seen to be monochromatic. 
Neither its shape nor brilliancy (in which it is deficient) are at 
all altered or impaired ; and it is especially interesting on this 
account, as there is something uncanny in the appearance of this 
pale flame defying the power of the prism, as it flickers aad plays 
about the brilliant spectrum representing the red-hot coals. 
Coals vary much in their possession of the source of this flame. 
In some it seems scarcely present at all, while in others it is 
abundant, being recognisable even in the large surface-flames. 
The coal in which I have seen it best, is a close hard coal, with 
a slaty cleavage and rectangular fracture, known, I am told, as 
“Anchor Brights” (?) The yellow flame appears frequently 
even in the largest surface ones, when the gaseous products first 
disengaged have disappeared. Some of them seem, then, to 
consist entirely of this, giving little or no continuous spectrum. 
But it is in the body of the fire that it is most fascinating, impart- 
ing a reality to the otherwise confused forms, which is more than 
pretty. Iam strongly reminded by this appearance, when, for 
instance, a black mass is seen to stand out with a clear out- 
line against the pale yellow background of light, of the 
picture which was mentally present in the days before the solar 
eclipse of 1868—the first upon which the prism was brought to 
bear. I have fortunately found a copy of some ‘‘ Instructions ” 
issued on the occasion of distributing the ‘‘ hand-spectroscopes ” 
provided by the Royal Society for the study of that eclipse ; in 
which this prognostication is indicated with quite as much pre- 
cision as the known facts at that time warranted, That it was 
not fully understood was the only reason why the moon was ot 
seen, as it might have been seen, on that memorable occasion, 
sharply outlined upon the coronal light, just as I now see the 
coal, This was long before the time when the same arrangement 
on a larger scale—a prism in front of the object-glass of a tele- 
scope—obtained such success in other hands. However that 
may be, the coal-fire experiment is a very pretty one, and might 
be made very instructive too as a drawing-room illustration—the 
ordinary prismatic pendants of a chandelier being quite equal to 
the oceasion, if a direct-vision combination is not immediately 
available. J. HERSCHEL 
30, Sackville Street, W. 
P.S.—As the monochromatic light—of sodium, of course—is 
plentiful in the large flames, it will be well seen as a Zine, straight 
or curved, if the light of the fire on a cylindrical or curved 
metallic or other reflecting surface be looked at, especially if 
dark coloured ; such as an ebonite ruler, for instance. Of 
course a direct-vision pocket spectroscope is better than the pen- 
dant of a chandelier ; but the lenses must be taken off, as well as 
the slit-screen. 
Complementary Colours —A Mock Sunset 
INSTANCES of two phenomena recently noticed in NATURE 
have chanced to come under my observation, and in each case 
impressed me much with their beauty and distinctness ; the first, 
an effect of contrast of colour on the surface of clear water. 
Standing looking up stream on a bridge over the Ary, where it 
flows through meadows close to Inverary Castle, and admiring 
the transparent brown hue so often seen in the peat-stained 
waters of Scotch streams, my attention was attracted by a series 
of wavelets forming a ridge, somewhat spiral in appearance, 
across the stream, along the top of a low weir over which the 
water falls. Every single wave presented on its further surface 
(that seen foreshortened by the spectator) a nearly level space of 
pure full-toned amethyst colour, while its advancing front showed 
with crystalline transparency the deep ‘‘cairn-gorm” or burnt 
sienni tint proper to the water. The regular alternation of 
these patches of rich and brilliantly-contrasted colours, together 
with their permanency and apparent independence of anything 
peculiar in the state of the atmosphere, produced a striking and 
very beautiful effect. 
The jhenomenon of a mock sunset in the east I witnessed in 
great perfection on the Lake of Lucerne, when the whole eastern 
sky was traversed by broad rose-coloured bands converging from 
the north, south, and zenith towards a point opposite pe 
A Lunar Halo 
LAST evening, about 7.15 p.m., a lunar halo of a peculiar 
character was seen here. It was at some distance from the 
moon, and instead of being, as usual, concentric with this body, 
was of an oval, or, more strictly speaking, a horse-shoe shape, 
the lower part of the halo not being complete. The moon, too, 
was not in the approximate centre of the horse-shoe. Suppos- 
ing its distance from the vertex to be represented by the quantity 
I, 24 would represent its distance to the lower part of the halo. 
Some heavy mist-clouds lay under the moon, which thinned out 
and became more transparent upwards, and refraction from the 
dense parts of these may have been the cau-e of the curious 
distortion of the circle in this case. J. RAND CAPRON 
Guildown, November 21 
A Correction 
PERMIT me to correct an error which appears in your report 
of “The Additions to the Zoological Society's Gardens ” 
(NATURE, vol. xxvi. p. 232). Your reporter states that one of 
the parrots presented by me is a ‘New Zealand parakeet 
(Cyanorhamphus nove-zealandie”). The bird I sent is Cyano- 
saissett, Verr., from hence (New Caledonia), and, according to 
Dr, Sclater’s published catalozue, has never been in the Gardens. 
It differs—as I have already pointed out—from C. xove- 
zealandi@ in size, extent of markings, but especially in the shape 
of the tail feathers (Cf. /ds, vol. 1879, pp. 109 110). It is one 
of a small group of parrakeets that is found in New Zealand, 
Chatham Island, Norfolk Island, and here, closely resembling 
each other, but at once separable when seen together. Neither 
this, nor Vymphicus uv@ensis, Layard, which is a new species 
just described by me, has ever been seen in Europe before, that I 
can learn. E, L. LAYARD 
British Consulate, Noumea, September 7 
[The Secretary of the Zoolozical Society informs us that Mr. 
Layard is quite right in his remark, but that the bird has been 
long since correctly named, and will be shortly figured in the 
Zoological Society’s Proceedings under its proper nane.—ED.] 
Thomson’s Mouse-Mill Dynamo 
ALLOW me to make a slizht but important correction on your 
description, in last week’s NATURE, of Sir William Thomson’s 
mouse-mall dynamo. In your description it is said that ‘‘at one 
end of the hollow drum these copper bars [the mouse-mill bars] 
are united to each other in pairs, each to the one opposite it.” 
This is not so. At one end of the hollow drum the ends of the 
copper bars are all united together, ‘ metallically connected by 
soldering or otherwise.” The effect is electrically the same as 
that of the arrangement described in your article; but, in the 
construction of the machine, the uniting of all the bars together 
at one end, instead of joining them in pairs, is so much more 
simple and ea-y that the correction seems of importance. 
J. T. BoTToMLEy 
The University, Glasgow, November 18 
