482 Bright Lines in the Spectra of Fixed Stars, [August, 
On September 1st the lines H a and were very intense 
in spite of the moist and disturbed state of the atmosphere ; 
H y was also distinguished. D 3 was no longer visible, but 
the dark sodium lines were seen. The latter, however, could 
not be measured, and subsequently they disappeared entirely 
like D 3 . The lines H a and were observed at the end ol 
September and in November, even in the most unfavourable 
circumstances. H T appeared also several times when the air 
was better, as well as the dark lines of the b group. _ 
The measurements which Herr von Gothard succeeded in 
executing on November 29th showed a displacement of the 
bright lines towards the red extremity of the spedtrum. 
The determinations were therefore repeated on December 
21st, with a very careful comparison with a Geissler tube 
filled with hydrogen. The comparisons were limited to the 
line , and gave for the wave-length of the line in the 
spedtrum of 7 Cassiopeise the value 486*5, and in that of 
the Geissler tube the value 4 ^ 5*9 j consequently a displace- 
ment of 0*6 millionth of a millimetre towards the red end 
of the spedtrum. 
In the spedtrum of /3 Lyrae, also, the bright lines which 
had vanished up to 1882 reappeared in August last year 
(1883). The lines H a and were very distindt on August 
26th, but they could not be distinguisned on September 28th, 
possibly on account of the great perturbation of the air. 
The next evening (September 29th) Herr von Gothard was 
surprised on witnessing the following phenomena : D 3 was 
brilliantly beautiful, the most intense of the three lines ; 
H^ was very fine ; but H a was very faint, scarcely visible. 
Occasionally a dark band was perceptible, lathei moie 
strongly refradtive than H a . In proportion to the general 
faintness of the spedtrum, the bright lines were much more 
intense than in 7 Cassiopeise. 
On Odtober 18th the bright lines D 3 and H /3 and the dark 
band were very distindt, notwithstanding the badness of the 
weather and the strong moonlight. This was the more re- 
markable as in the previous year the seaich for these lines 
had been unsuccessful, even in the most favourable weather. 
On Odtober 26th, with a large new spedtroscope, the bright 
lines D 3 and H^ and the dark sodium lines were still very 
distindt. 
On November 21st occurred another unexpeaed change. 
Herr von Gothard could find only the bright line H^, and 
this with great difficulty ; D 3 and H a were vanished. On 
