312 
or outer, twilight, extending in reality to far beyond and above 
the place of the said cloudlets, was on this occasion painted, or 
blocked, out by dark dun colour. Nearly half the heavens were 
so obscured, and the earth below was as dark. No wonder 
then that the residual strip of untouched twilight shone so 
conspicuously in contrast. 
But what is that darkness below an auroral are ? 
It has been compared to the dark space under the negative 
pole of a highly rarefied gas-tube, when an electric spark is 
passed through it, And if we add in idea that it extends 
downwards to a certain angular distance from the sun, say 20°, 
and keeps to that,—the suggestion may explain why the silver- 
blue cloudlets were seen higher over the northern horizon in the 
end of June and beginning of July, than at vhe end of the 
latter month ; and also why they are never seen in the winter. 
But a still greater instrumental curiosity manifested itself in this, 
that the bright auroral citron-coloured line was also given in the 
spectroscope out of every part of that large expanse of auroral 
shade ; and almost, though not quite, as well as from the bright 
track along its outer and upper edge ; just as if, however dark 
to the unassisted eye, the black-brown space was yet somewhat 
luminiferous to the peculiar power of the prism. 
On the next night after this interesting midnight experience, 
there was no aurora, and the twilight extended faintly to many 
degrees higher than the position of the blue clouds of the 
previous night, and in fact spread into and over the region which 
was before so decidedly ‘‘aurora blackened.” 
But the next night after that again, viz. two nights after the 
display, there was a wet drizzling mist which continued through 
the early hours until more than a quarter of an inch of rainfall 
had been gathered. Admirably confirming therefore the late 
Sir Robert Christison’s often strongly expressed opinion that 
48 hours after a great aurora, abundant rain is sure to follow,— 
an opinion too which I have only just heard was formed quite 
independently in Canada by my friend Mr. R. S. Haliburton, 
who is even now introducing it into his theory of ‘the aqueous 
origin of the aurora,” so far as that can be carried; but with- 
out explaining either the citron line in the spectrum; or the 
effect on the magnetic needle. C. Prazzt SMYTH 
15, Royal Terrace, Edinburgh, July 31 
The Bright Clouds 
THE bright cirrus-like clouds are very common here this 
summer. I have seen them here on the nights of the r2th, r8th. 
2oth, and 24th of last month, and on the rst inst., also at 
Gilsland on the 27th ult., in fact I do not know that in the last 
fortnight there has been a single night on which the northern 
sky has been quite free from lower clouds on which they have 
not appeared more or less ; sometimes, however, they appear 
but fora short time, and ina very limited area of the sky. I 
have tried to keep a watch to see them in the day-time, but have 
not succeeded as yet; the nearest approach to success was on 
the 20th ult., when I saw them as early as 9.22 p.m., at which 
time they were visible over the greater part of the sky, but in 
the south-east were not strikingly bright. 
There is one peculiarity with respect to them that I have not 
seen mentioned in NATURE, and that is their motion; on the 
above dates, except the 2oth, I took notice of this, and in every 
instance the motion was from a northerly or easterly direction, 
whereas I have not noticed any ordinary cirrus moving from 
that quarter lately. Last night at from ro to 10.15, when there 
were small patches of these curious clouds, there was also at the 
same time a great deal of ordinary cirrus moving from the west. 
This circumstance appears to indicate that there is quite a 
different current of wind in the upper atmosphere from that 
blowing at the lower elevation of ordinary cirrus. 
I have no hesitation in saying that these extraordinary clouds 
do not shine with their own light, but with the direct light of the 
sun. T. W. BACKHOUSE 
Sunderland, August 2 
Aurora 
THE following is a record of aurora observed on July 27 at 
Ramelton, co. Donegal :— 
9.30 p.m.—From west to east there were occasional pencils 
of reddish lights shooting up, while from east to west there were 
NATURE 
[August 5, 1886 
continuous pencils of yellowish and reddish lights, with inter- 
mittent clouds and columns of reddish light, rising between the 
north-east and north-north-west. The pencils were very steady, 
but increasing and decreasing in length, at times assisted by the 
clouds of red forming a corona at the zenith round the star 
Capella (?), at such times as pencils shot up from the southward, 
on a rude irregular cross. The corona and cross appeared and 
disappeared quite rapidly. The clouds and columns of reddish 
light were succeeded by flashes and pencils of bright silver light, 
they being most frequent and brilliant between the north and 
west, the flashes being sometimes in long narrow wavy clouds 
that rapidly ascended, or narrow sheets that appeared and dis- 
appeared nearly instantaneously. They became more and more 
brilliant, especially to the north-north-west, till the display was 
greatest between 10.30 and 10.45. ; : 
10.45 p.m.—About this hour the continuous pencils of yellow 
and reddish lights between the east and west disappeared with 
the other lights, but about five minutes afterwards, to the north- 
ward, silver pencils and sheets appeared, veering from thence 
gradually towards the north-east and east. Some of the sheets 
hung at times in clouds that formed small ares, that slowly rose 
obliquely, and moving eastward till about 11 o'clock, when all 
the lights disappeared, except that at long intervals faint pencils 
or flashes might shoot up on a small are of silver clouds; 
but at 11.25 there was another brilliant display. First there 
appeared an arch of silver light, its centre being about north- 
north-west, then two arches that began sending up horns and 
pencils of light. The upper arch was a little below the North 
Star, while the lower one went through the Pointers of the Plough ; 
these two arches were succeeded by one at 11.35. The crown of 
the arch was very unsteady, moving from north to north-north- 
west and back again, its shape and the accompanying borns and 
pencils continually changing, the most brilliant and highest 
pencils being those that shot up to the north-westward. This 
display continued more or less brilliant till 11.45, when clouds 
came up and prevented further observations ; but at midnight 
the position of an arch was distinctly defined behind the clouds. 
At I a.m. the clouds had cleared away and no lights were 
vi-ible. The night was not favourable for seeing an aurora, as 
it was very light and clear, yet at times the lights were very 
brilliant. Although the arches were of the same class of silver 
light as those seen from the North Atlantic or the Canadian 
Lakes, yet they were not steady like those, as they were con- 
tinually shifting their positions or disappearing and reappearing. 
During the previous day there was a northerly wind with at 
times intensely cold squalls of misty rain, 
G. H. KINAHAN 
ABOUT [1.15 p.m. July 27, 1886, I observed an incipient 
stage of the aurora borealis, and about <.10 a.m. of the 28th a 
considerable display of auroral colour commenced ; but between 
0.30 a.m. and 1 there was a vivid display of huge auroral sheets 
and columns ; indeed, it did not require much to entitle the 
golden scene to the epithet—magnificent. There was a pris- 
matic arc, not unlike a rainbow, which spanned from the north- 
west to the east, and measured about 70° from its centre to the 
horizon. All under this arc was a flood of white light, which 
the aurora did not in the least degree invade. From this are 
developed a brilliant aurora borealis to a few degrees south of 
the zenith ; and, with other constellations, Cygnus, Lyra, and 
the Northern Crown were overwhelmed in a golden flood. In 
this part of our northern latitude there are at present highly 
favourable conditions for phenomenal refraction of solar light. 
On the morning of the 27th and 28th the earth-shine on the 
moon was very bright, and I have no doubt but that these atmo- 
spheric conditions are also favourable to auroral displays. Every 
vestige of the aurora borealis disappeared about 2.30. 
I do not think that an aurora as early as July is on 
record; in the Culloden meteorological records there is not 
one recorded so early as July from 1841 to 1S8o; indeed 
August is reckoned unusually early for an aurora borealis. 
I recollect a most magnificent one about the beginning of August 
in 1882, in the upper reaches of Lanarkshire; the huge vivid 
sheets and columns reached from the west all along the horizon 
to the east, and up the vault of heaven to the zenith, and with 
their fleet shifting flashes and bursts of prismatic coruscations, 
they lighted up the earth with ineffable glory. 
DoNALD CAMERON 
The Academy, 22, Argyll Street, Paisley, July 28 
