5. A faint line or band in the green, between b and F. W.L., Barker, 5020 (chromospheric?).
6. A line in the green-blue, at or near F. W.L., Alvan Clarke, jun., 4850.
7. A line in the indigo, at or near G. W.L., Alvan Clarke, jun., 4350.
8. The continuous spectrum from about D to beyond F.
Dr. H.C. Vogel’s observations of Auroral lines. Spectrum described.
Dr. H. C. Vogel, formerly of the Bothkamp Observatory, near Kiel, and since of the Astrophysical Observatory, Potsdam, made several observations of the Auroral lines, October 25th, 1870. Besides the bright line between D and E, he found several other fainter lines stretching towards the blue end of the spectrum on a dimly-lighted ground. February 11th, 1871, he observed the same set of lines, and an average of six readings gave 5572 as the W.L. of the Ångström line. February 12th gave 5576 as Dr. Vogel’s reading, and 5569 as Dr. Lohse’s. April 9th gave 5569, and April 14th 5569. The Aurora of April 9th, 1871, was exceedingly brilliant, so that micrometer measurements of the lines were taken. The spectrum consisted of one line in the red, five in the green, and a somewhat indistinct broad line or band in the blue. The lines are thus described:—
Table of lines.
Table of Dr. Vogel’s lines. Aurora, April 9th, 1871.
| W.L. | Probable error. | Remarks. | |
|---|---|---|---|
| 6297 | 14 | Very bright stripe. | On a faintly lighted ground. |
| 5569 | 2 | Brightest line of the spectrum, became noticeably fainter at appearance of the red line. | |
| 5390 | .. | Extremely faint line; unreliable observation. | |
| 5233 | 4 | Moderately bright. | |
| 5189 | 9 | This line was very bright when the red line appeared at the same time; otherwise equal in brilliancy with the preceding one. | |
| 5004 | 3 | Very bright line. | |
| 4694 | 3 | Broad band of light, somewhat less brilliant in the middle; very faint in those parts of the Aurora in which the red line appeared. | |
| 4663 | |||
| 4629 | |||