- 
° 
182 
considerable electric tension in theatmosphere at the time, The 
weather was also remarkably dry. 
Trebizond, Dec. 15, 1872 
W. GIFFORD PALGRAVE 
The Spectrum of the Aurora and of the Zodiacal Light 
Upon a perusal of the chapter in Dr. Schellen’s ‘*Spectrum 
Analysis,” specially bearing on the above subjects, I have been 
Jed to think—firstly, that our present knowledge of these spectra 
is far from complete ; and secondly, that so far as such know- 
ledge extends, it hardly warrants some of the conclusions arrived 
at in Dr. Schellen’s work. To test the question of the aurora, 
T have collected, chiefly from the pages of NATURE, a set of 
observations (excluding a few which gave only rough results), 
and have arranged them under the heads of the several lines, so 
that these and their characteristics may be seen at a glance, and 
the observations compared ; and from these observations I de- 
duce the following remarks :— d ; 
1. That the full spectrum of the aurora consists of seven brig ht 
lines or bands and a faint diffused spectrum. 
2. That two (perhaps three) of these lines are sharp and well 
defined, while the others are more or less nebulous. (As Lord 
Lindsay notes one of the lines to be sharp on one side and nebu- 
lous on the other, itis probable that this, and perhaps others of 
the nebulous lines, would resolve into groups of lines under 
higher instrumental power. ) . 
3. That the red line (which seems to have been actually posi- 
tioned by two observers only) is not found to coincide with the 
spectrum of any known substance or gas. (But see next note.) 
4. That the yellow-green aurora line, and perhaps two other 
lines, according to one observer, coincide with lines of oxygen ; 
while two lines, according to other observers, either fall very near 
to, or actually coincide with, F and G hydrogen, and that to this 
extent theaxiom of Zdéllner, that the spectrum of the aurora does 
not agree with any of the known spectra of the gases of our 
atmosphere, is challenged, : é 
6. That Zollner’s theory of the lines or bands in the blue being 
remains of a continueus spectrum broken up by dark absorption 
bands, is hardly supported by the other observers. 
4. That the aurora spectrum is probably a mixed one, and 
that the red and yellow-green lines are independent spectra ; as 
also may possibly be the corona line and the continuous spectrum 
crossed with the fainter lines. 
8. That the discrepancies in the observations recorded are con- 
siderable, and that all the lines (except, perhaps, Angstrom’s), 
and specially the red one, require further examination to confirm 
their position. 
And this last proposition I venture to commend to the atten- 
tion of your spectroscopic correspondents during this winter. 
The zodiacal light will also undeniably bear further investiga- 
tion, The evidence at present seems to strongly incline to the 
presence of a faint continuous spectrum only. Webb, Back- 
house, and Pringle are positive in their observations as to this ; 
and, on the other hand, the bright green line referred to by Dr. 
Schellen, as seen by Angstrém and Zollner zz all parts of the 
sky can, as Pringle has well noticed, hardly be assumed to 
belong conclusively to the zodiacal light, but rather to some 
faint accompanying aurora. I ain not aware whether the zodi- 
acal light and the aurora have been examined with a polariscope. 
The light, though faint, might, I imagine, be tested with a 
Nicol’s prism and Sayart bands. An observation of the zodiacal 
light in the spring showed me its faint rose-red tint very distinctly, 
although I was not at that time aware that this tint was cha- 
racteristic, ; é 
AURORA SPECTRUM 
No, 1.—:4 Line in the Red between C and D 
OBSERVER. REMARKS. 
T, F. (Torquay). Strong, intermediate in colour and posi- 
tion to lithium and calcium. 
J. RB Cc. Like lithium line, but duskier ; well seen 
in Browning’s miniature spectroscope ; 
sharp and well defined. 
BARKER. Almost equidistant between C and D; 
wave-length, 623" (C and D being re- 
* A line of nitrogen in the air spectrum seems to lie very close to this 
position, and if other lines lie so near to, or coincide with, those of oxygen 
and hydrogen, it would appear not unreasonable, until further evidence is 
obtained, to conjecture that the Aurora Spectrum may be wholly or in part 
an air spectrum modified by temperature pressure.—J. R. C, 
“Db Oe gee ee ee 
, 
NATURE 
[Fan. 9, 1873 
spectively 656 and 589); sharp and 
well defined ; brightness 3 (counting 
from 1 as brightest). 
At 24; Ha being 18, and Na 32. Does 
not coincide with any other line ob- 
server has see 
Between sodium and lithium, but nearer 
PROCTOR, 
PIAzzI SMYTH. 
the latter. Estimated at W.L. 6350. 
| BACKHOUSE, Seen in eight auroras, out of thirty-four 
; observed. 
ZOLLNER. More refrangible than Ha ; possibly lies 
(Schellen. ) near the dark telluric lines A ; wave- 
length, 6,279 (Angstrom), 
No, 2,—A Line in the Yellow Green between Dand E (principal 
auroral line) 
Strong; pale yellow near D, 
Sharp and well defined ; like principal - 
line in nebulze, but brighter ; a peculiar 
flickering noticed in the line during the 
displays of Oct. 1870 and Feb, 1872. 
ALVAN{CLARK, JUN. ‘ Wave-length, 569. (Probably an error — 
for 559.—J. R. C.) 
T. F. (Torquay). 
[aniss 0c. 
BARKER. Wave-length, 562; sharp and well de- 
fined ; brightness, r. 
PRocror. At 41 (Na being 32); nebulous ; abso- 
lutely coincident with a line in a lu-— 
miére tube attributed to oxygen. : 
Sharp and well defined ; visible with very 
narrow slit. 
Within a few units of Kirchhoft’s 1255; 
a peculiar flickering, and frequent 
changes of brightness. 
Over citron acetylene, at W.L. 5579. 
Lorp LINDsAy. 
HERSCHEL. 
Prazzi SMYTH. 
ScHMID?. Varied much in intensity. 
(Schellen. ) 
ZOLLNER. Brilliant in all parts of the aurora. 
(Schellen.) > 
No. 3.—A Linein the Green near E (corona line ?) 
ALVAN CLARK, JUN. At 532; assumedjto be 531°6 (corona 
ine). 
Notes three lines in the aurora as coinci- 
dent with corona lines. 
Near E. ; woolly at the edges, but rather - 
sharp in centre ; at or near 1474 of the 
corona. 
Once only, at 532. 
WINLOCK. 
(Schellen.) 
Lorp LInpDsay. 
BACKHOUSE, 
No. 4.—A Line in the Green at or near b 
ELGER, Very faint ; half way between principal 
auroral line and F. i 
BARKER. At 517. (Assumed to be 520.—Win- 
lock.) Nebulous ; brightness, 5. 
Lorp LINDSAY, A faint band coincident with 4, and ex- 
tending equally on both sides of it. 
A faint band at 57, Na being 32 and Hg 
75, coincident with a line (of oxygen ?) 
in lumiére tube. 
PrRocTor. 
No. 5.—A Line in the Green betweenb and ~ 
BARKER. At 502; brightness, 2; conjectured to 
coincide with a line in the chromo- 
sphere. 
BACKHOUSE, Mentions a faint band seen in five auroras 
out of thirty-eight at 500 or 510 (Sor? 
—J. R. C.) 
No. 6.—A Line in the Green-Blue at or near F 
ELGER. Faint and nebulous. 
ALVAN CLARK, JUN. At 485; assumed to be 486 F hydrogen. 
BARKER, At 482; assumed to be 485 of Alvan 
Clark, jun. 
At 81; more refrangible than Hf (75).4 
Very slightly more refrangible than F ; 
side towards D sharp and well defined ; — 
other side nebulous, 
PROCTOR. 
Lorp LINvsAy. 
by 
x, 
