‘ALOGUE OF BRIGHT LINES IN THE SPEC- 
TRUM OF THE SOLAR ATMOSPHERE * 
\\/ITHOUT waiting to complete my entire report of the spec- 
*™* troscopic work at Sherman, I send for immediate publica- 
m, should you think proper, a list of the bright lines observed 
in the spectrum of the chromosphere during the past summer. 
_ The great altitude of the station (nearly 8,300 ft.), and the 
consequent atmospheric conditions, were attended with even 
advantages for my special work than had been really ex- 
ed, although I was never quite able to realise my /ofe of 
seeing all the Fraunhofer lines reversed ; unless once or twice 
or a moment, during some unusual disturbances of the solar sur- 
face. Everything I saw, however, confirmed my belief that the 
origin of the dark lines is at the base of the chromosphere, and 
at the ability to see them all reversed at any moment depends 
erely upon instrumental power and atmospheric conditions. 
In this view, a catalogue of the bright lines actually observed 
5 of course less important than it would be otherwise ; still it is 
not without interest and scientific value, since the lines seen are 
urally those which are really most conspicuous in the chro- 
spectrum, and this conspicuousness stands in important, 
y no means obvious or even entirely simple, relations to 
the intensity of the corresponding dark lines, when such exist. 
‘There can be no doubt that a careful study of these bright lines 
‘and their behaviour would yield much valuable information as to 
the constitution and habitudes of the solar atmosphere. 
In the catalogue, the first column contains simply a reference 
number : a { refers to a note at the end of the catalogue. 
The numbers in the second column refer to my ‘‘ Preliminary 
Catalogue,” containing 103 lines, which was published a year 
ago in the American Fournal of Science. In this column a + 
indicates that some other observer has anticipated me in the 
determination and publication of the line. As I have depended 
for my information almost solely upon the Comples Rendus 
d the Proceedings of the Royal Society (which give the ob- 
ervations of Lockyer, Janssen, Rayet, and Secchi), it is quite 
possible that some other lines ought to be marked in the same 
manner. 
_ The third column, headed K, gives the position of the lines on 
chhoff’s scale, the numbersabove G being derived from Thalen’s 
mtinuation of Kirchhoff’s maps. In this column an asterisk de- 
notes that the map shows no corresponding dark line, a ? that the 
exact position, not the existence, of the line is for some reason 
ightly uncertain, 
The fourth column, headed A, gives the wave-length’of the line 
in ten millionths of a millimetre according to Angstrém’s atlas. 
he numbers in this and the preceding column were; taken, 
not from the maps themselves, which present slight inaccuracies 
on account of the shrinking and swelling of the paper during 
the operation of printing, but from the numerical catalogues of 
Kirchhoff and Angstrom which accompany their respective 
tlases. In the preliminary catalogue the numbers were derived 
from the maps; hence some slight discrepancies in the tenths 
of division. 
_ The fifth column, marked F, contains a rough estimate of the 
percentage of frequency with which the lines were seen during 
six weeks of observation ; and the sixth column, B, a similar 
estimate of their maximum brightness compared with that of the 
hydrogen line C. 
_ The variations of brilliance, however, when the chromosphere 
as much disturbed, were so considerable and so sudden, that no 
very great weight can be assigned to the numbers given. Nor is 
it to be inferred that lines which have in the table the same index 
f brightness were always equally bright. On some occasions one 
of lines would be particularly conspicuous, on others, another. 
With two or three exceptions, indicated in the notes, no lines 
have been catalogued which were not seen on at least two dif- 
ferent days. In the few cases where lines observed only on one 
Occa,ion have been admitted to the list, the observations were 
tt the time carefully verified by my assistant, Prof. Emerson, 
50 as to place their correctness beyond a doubt. Many other 
lines were “ glimpsed” at one time and another, but not seen 
teadily enough or long enough to admit of satisfactory deter- 
ation. 
The last column of the catalogue contains the symbols of the 
chemical elements corresponding to the respective lines. The 
0 
u 
~ * Letter to the Superintendent of the U.S. Coast Survey, containing a 
Catalogue of Bright Lines in the Gar of the Solar Atmosphere, observed 
‘at Sherman, Wyoming Territory, U. S. A., during July and August, 1872 ; 
by Prof. C. A. Young, of Dartmouth College. Reprinted from advance 
‘sheets of the American Yournal of Science and Art. 
materials at my disposal are the maps of Kirchhoffand Angstrém, 
Thalen’s map of the portion of the solar spectrum above G, and 
“ Watts’s Index of Spectra.” Since’the positions of the lines in 
the latter work are given only to the nearest unit of ‘‘ Ang- 
strom’s scale,” I have marked the coincidences indicated by it 
with a(w), considering them less certain than those_shown by the 
maps. 
In addition to the elements before demonstrated to exist in the 
chromosphere, the following seem to be pretty positively indi- 
cated—sulphur, cerium, and strontium; and the following with 
a somewhat less degree of probability, zinc, erbium, and yttrium, 
lanthanum and didymium. There are some coincidences also 
with the spectra of oxygen, nitrogen, and bromine, but not enough, 
considering the total number of lines in the spectra of these ele- 
ments, or of a character to warrant any conclusion. One line 
points to the presence of iridium or ruthenium, and only three 
lines are known in the whole spectrum of these metals. The 
reversal of the H’s deserves also especial notice. 
No one, of course, can fail to be struck with the number of 
cases in which lines have associated with them the symbols of 
two or more elements. The coincidences are too many and too 
close to be all the result of accident, as for instance in the case 
of iron and calcium, or iron and titanium, 
Two explanations suggest themselves. The first, which seems 
rather the most probable, is that the metals operated upon by 
the observer who mapped their spectra, were not absolutely 
pure—either the iron contained traces of calcium and titanium, 
or vice vers@. If this supposition is excluded, then we seem to 
be driven to the conclusion that there is some such similarity 
between the molecules of the different metals as renders them 
susceptible of certain synchronous periods of vibrations—a re- 
semblance, as regards the manner in which the molecules are 
built up out of the constituent atoms, sufficient to establish 
between them an important physical (and probably chemical) 
relationship. I have prefixed to the catalogue a table showing 
the number of lines of each substance, or combination of sub- 
stances, observed in the chromosphere spectrum, omitting, how- 
ever, oxygen, and nitrogen, and bromine, since with one excep- 
tion (line 230), neither of them ever stands alone, or accounts 
for any lines not otherwise explained. 
The instruments and methods of observation were the same as 
those employed in the construction of the Preliminary Catalogue. 
Telescope, 9 x4; inches aperture—spectroscope automatic, with 
dispersive force of 12 prisms. 
The approximate geographical position of Sherman is long. 
th, 53'2m. west of Washington, 'lat. 41° 07’ ; altitude above sea- 
level 8,280 feet ; mean height of barometer about 22°1 inches, 
Table showing the number of coincidences between the bright lines 
observed in the spectrum of the chromosphere, and those of the 
spectra of the chemical elements, 
Fe, Ti,’ Siwy | 1 Ti, Sw) 3 |\Unknown.| 52 [ fetal. 
So Bay Stay | ¥ ce Ga 2 |————! 
© Sew) Znqw)| I Sein: I Fe, 64 | IIo 
** ‘Go, Ce I > Ge; I Ti, 23 43 
bec Fs OF Sh a Ca, | To 2 
Gay. Cx; Ce; I eis) Ba, 8 13 
> Ly. Zu, I a Et. I Siw) i) 14 
Ti, Ba, Siw) I Mn, 6 12 
Ba, La, E(w) I Ca, Cd, I Ce, 5 II 
“* Ce, I H, 4 4 
Fe, Ca, | 10 Ca, Co, I Na, 4 6 
iuf 9 -Cr a Cs 4 | Io 
“~Mn,| 4 “Sr, I Mg, 3 4 
“Cr, 5 Sr, 3 6 
“ Ni, | 3 | Sw Eqy | 2 Zn, 3 9 
se es a hae Ew) 2 9, 
Sa Frat e a Mn, Zn, I Ni, 2 6 
“ Eq) | 2 Co, I 5 
Cr, E(w) I Cu, I 2 
in Ge; I | _ La, I 3 
&> Co; I Ce, Co, I Ru, Ir, I It 
§ Mg, I Cd, I 
Sa I Na, Cu, I Li, I 
“ Sim I j : 
“ La, | 1. {lines marked | 
with an * | 14 | 
The numbers in the last column denote the whole number of 
times that the symbol of each element appears in the catalogue, 
either singly or combined with others. Laas 
