Dec. 7, 1882 | 
Havinc read in the English journals how very extensively 
and simultaneously the remarkable display of aurora borealis 
was observed in Europe and the United States, I beg to 
forward the inclosed report from Prof. Tacchini (see be- 
low), taken from a newspaper in Rome, describing that 
splendid pheno.nenon as it appeared in this country on the 
evening of the 17th inst , which probably may interest some of 
your readers. 1 would merely add that on the evening in ques- 
tion I was travelling between Spezzia and this city, when my 
observation was absorbed by the brilliancy of the beautiful phe- 
nomenon as seen from a railway carriage, and which accords 
very closely with the appearance of it in Rome. Soon after 
sunset the north-western sky was diffused with richly-coloured 
roseate tints blending into crimson at the horizon, which con- 
tinued up to 7 p.m. ; the transparency of this apparently roseate 
cloud was a’so a very remarkable feature, for the stars of the 
Great Bear were seen throug it with little diminution of lustre ; 
the sunset was very noticeable, which I remarked before branch- 
ing from the coast where I had the sea horizon, and I never saw 
a more distinct and clzar disappearance of the sun at sea below 
the horizon, even t» the clearness of the atmosphere. Aurora 
borealis is so seldom seen in this country that its appearance 
cause much public curiosity. ERASMUS OMMANNEY 
Florence, 12, Lungarno, November 30 
THE following account of aurora borealis, seen on the 17th 
ult., atthe Observatory of the Roman College, was sent by Prof. 
‘Tacchini to the Roman journals :— 
“Yesterday evening (the 17th), a few hours after sunset, a fine 
aurora borealis appeared on our horizon. Besides the magui- 
ficent rosy arch melting away above, I saw, below, the so-called 
dark segment, which had a most lovely azure-greenish colour. 
“At 5h. 50m. the red ribband rose more than 30° above the 
horizon, but at 5h. 55m. clouds suddenly covered almost the 
whole of that part of the sky occupiei by the aurora, and a 
storm, with lightning, arose in the north. At 6h. 18m. there 
was a slight clearance, and through the aurora, which had 
already paled, shone sone of the stars of Ursa Major, The 
highest point of the dark segment was precisely between the 
stars a and ¢ of that constellation, being about 14° above the 
horizon, and 17° from the north towards west, therefore nearly 
in the direction of the magnetic meridiin, and with an amplitude 
of about 45°. The weather continued bad, and at intervals rainy, 
and at 6h. 32m. were seen the last traces of the phenomenon. 
From the auroral light ouly a very faint continuous spectrum 
could be obtaine’, but I could not make such observations at 
the most opportune moment. 
“* Several falling stars were oDserved through the aurora. A 
magnetic perturbation occurred yesterday, and in the nizht, and 
continued also to-day ; and, moreover, there is on the sun a 
aie spot, easily vi-ible on using merely a piece of sm>ked 
glass. 
“The large diameter of this spot is slightly less than the thir- 
teeuth part of the apparent diameter of the solar disc. The 
spot appeared on November 12, at the eastern limb in the sun’s 
boreal hemisphere, and on the 12th and 13’h magnetic perturba- 
tions occurred. Yesterday I could not observe it well, because 
of the bad weather; but the day before, clouds of hydrogen 
were seen on its nuclei, and this morning still the phenomenon 
is most brilliant, demonstrating the greater intensity of solar 
phenomena over the spots in the atmosphere of the sun, which 
may thus be called solar auroras. 
_ “‘ Again, the magnetic perturbation of yesterday and last night 
is connected with that vast storm depression, which embraced a 
great part of Central Europe and especially Italy. 
** We will further record here, that in the beginning of last 
October another ausora borealis was observed, and that then 
also there were strong magnetic perturbations in the earth, 
and large spots on the sun, seen on the limb on September 25. 
“* The Director of the Telegraphs has announced that very great 
perturbations occurred yesterday on all the lines, and from 
Belluno, Milan, Turin, Moncalieri, Venice, Porto Maurizio, 
Parma, Modena, Genoa, Luveno, and Viesti have come tele- 
grams, showing that in the north the phenomena must have 
been very splendid From Venice the Director of the Observa- 
tory states that yesterday morning at 4 o'clock, gl-ams of auroral 
light were observed. “© P. TACCHINI 
“Observatory of the Roman College, November 18 ” 
I aM afraid you must have been overburdened with auroral 
co.nmunicaticns, but perhaps you will kindly allow me on this 
N ATURE: 
39 
occa-ion a little more space. Mr. E. Dowlen witnessed at 
Medway, Poynton, Cheshire, but little of thit of the 17th; but 
on the 13th saw an auro-al haze with shafts of white light, at 
6 p.m. in the north and north-west. This had been preceded 
by a rose-red sunset, unlike an ordinary one, and accompanied 
by magnetic clouds. He also noticed an auroral glow on several 
subsequent nights. 
On Friday last (the 24th) the Rev. W. Pearce saw a fine 
aurora at West Horsley, about six miles east from here. It 
commenced about gh. 15m. bya yellow glow in the north-north- 
east and north-north-west, which increased in brightness and 
rose upwards, until at 9h. 30m. the Great Bear was hidden by 
it. It then changed to a rose lint, and spread laterally ; was at 
its greatest brilliancy at gh. 50m., and disappeared at toh. 15m. 
Mr. Prince, of Crowborough (who, from the movements of 
certain insects and the magnetic di turbances, anticipates a 
severe winter), remarks that the ‘* bright beam » must have been 
like a row of patches of light he saw on last October 3, south- 
ward and nearly parallel with the auroral arch northward. As 
some of your correspondents seem to ascribe a meteoric charac- 
ter to this beam, I may add I examined it carefully with a large 
Browning direct-vision spectroscope designed for auroral o)ser- 
vations, and fouid only the well-known citron line, and none 
other, Alsoa faint greenish-white continuous spectrum extend- 
ing a short way from that line towards the violet. ‘Lhis might 
have been auroral or from moon reflection. I had just pre- 
viously examined the sky in that direction, and found no auroral 
line. 
Mr. Saxby’s letter is interesting in fixing approximaiely the 
po-ition and height of the beam, especially when read in connec- 
tion with Messrs. De la Rue and Miilier’s vacuum experiments 
and their table of heights assigned to auroree, and it is still para- 
doxical that if such electric displays be within the limits of our 
atmosphere the air-spectrum is conspicuous for its absence, while 
it is replaced by one the principal line of which is not found in 
any other form of matter in the sky or on the earth. 
On the other hand this point would not be inexplicable if the 
aurora be considered a something fey se, as, for example, phos 
phorescence (stronzly marked in the recent aurore), excited by 
the electric discharge. That in such case it might wholly or in 
great part appropriate the spectrum to itself is shown by the 
instances of indium, thaliium, and some other volatile metals 
which, when used as electrodes for the c mdensed spark, give 
spectra ia which the a r lines are either absent or faint, and wher 
burnt in the are have a similar effect on the carbon lines. Ihave 
elsewhere pointed out the probability of the aurora being refer- 
able to a form of phosphorescence. 
The moonlight was unfortunate as regards the masking the 
fainter lines of the spectrum. I see one record of a faint red 
line, but except this of no other lines. If any of your readers 
have fixed the other lines, you will no doubt find space 
for so important an observation, for it is curious how little 
we know of the exact positions of these. I believe the 
measurements of a full set of the auroral lines made by 
my friend Prof. Vogel of l’otsdam, in April, 1872, stil 
remain the only standard, and as we now seem at an auroral 
peri d I would earnestly urge uyon spectroscopists their special 
attention to the-e fainter line , with a view to fixing their posi- 
tions. This, too, is important, as there is a suspicion they are 
not always the same in different displays. The mode of doing 
this is not, however, very easy. If the spectroscope. is of very 
small dispersion, the lines will be too close for useful measure- 
ment. With one of larger dispersion the introduction of a 
comparison spectrum or an illuminated micrometer scale will 
swamp the lives. A single illuminated point or line working 
across the field, the eclipsing the lines successively behind a 
diaphragm of tinfoil (as suggested by Mr. Lockyer), and a scale 
photographed on thin glass, through which the lines are seen, 
and which is itself illuminated by the spectrum, are severally 
better methods, and might perhaps yield some available results. 
Guildown, Guildford, December 1 J. RAND CAPRON 
THE unique nature of this meteor must be the excuse for 
adding another letter on the subject. Your correspondents, Mr. 
Taylor of Heworth Green, York, and Mr. Elger of Kempton, 
have kindly answered queries of mine as to the exact place of 
the passage ; these s'ations being the most important, after the 
transit stations of Woodbridge and Old Windsor, After Mr. 
Saxby’s letter of November 30, any farther notice may seem 
superfluous, were it not that the elements he assizns cannot 
explain the observations. At York the meteor could not have 
