340 
CAPTAIN L. DAEWIN, DR. A. SCHUSTEE, AND MR. E. W. MAUNDER 
Now almost the three strongest corona groups occur exactly at the same places as 
the groups 2, 3, and 4. When we compare the individual lines within each group, 
however, the agreement is not so satisfactory, and the defective coincidence in 
group 3 argues strongly against its reality. The strongest corona line is at 4232'8, 
falling in the middle between the two nitrogen lines; hut the line 4228 is really a 
weak nitrogen line, and while the other two are about equally strong and so broad, 
at any rate at atmospheric pressure, that they would not be separated on our 
photographs, but show as a broad band with 4239 as centre, I conclude that the 
strongest corona line can have nothing to do with nitrogen; and this makes the other 
coincidences very doubtful, especially as the strongest of all violet nitrogen lines at 
3994’5 has no representative in the corona spectrum. Nevertheless, I think it 
would be worth while to look for tlie strong green nitrogen line in the spectrum of 
the corona on the next occasion. I have also examined the spectrum of oxygen, 
finding a number of curious coincidences which are also very likely accidental only. 
Finally, there are some of the corona lines which seem to lie very near lines of 
manganese. As Mr. Lockyer has shown that the spectrum of manganese plays an 
important part in cosmical spectroscopy, the coincidences deserve careful consideration. 
I have, therefore, added a column for the manganese lines in the above Table. The 
strongest manganese lines in the violet are 4235'0 and 4230'7 ; the mean of these two 
numbers is 4232'85, or exactly at the place at which the strongest corona line is placed. 
I think that our o})inion as to the presence of manganese in the spectrum of the 
corona must depend on the question whether the two manganese lines could possibly, 
with the instruments used, look as a single line. My own opinion is against such a 
view. Our photograph resolves lines which are quite as close or even closer together 
than the two lines in question, which are quite sharp. The corona line on our plate 
has a certain width filling a space between 4231 and 4235'0, that is to say, it fills 
exactly the two spaces between the two manganese lines, but does not overlap them. 
It is strongest near its centre. From the width of the slit used, I calculate that an 
indefinitely thin line would, in this part of the spectrum, cover a space of about 
2'6 units, so that the manganese lines should he separate, and reach respectively from 
4228'4 to 4232*0, and from 4233*7 to 4230'3. The corona line should, therefore, 
show very decided signs of duplicity, and I cannot reconcile its actual appearance 
with the supposition that it is the representative of the two manganese lines. For the 
present, then, our attempt to identify corona lines has only led to negative results. 
4. Summary of Results and Suggestions. 
In conclusion, I give a summary of the principal results of the spectroscopic 
camera, together with a few suggestions which may prove useful to future eclipse 
observers. 
