544 Proceedings of Boyal Society of Edinburgh. [sess. 
The agreement between observation and computation is so ex- 
traordinary that the observers felt justified to remark : “ There 
is, then, no evidence that the position of the band is affected by 
other considerations than that of wave-length.” 
A similar result is obtained from the investigation of the 
bright bands. According to theory, the enormous width of these 
bands, as well as the appearance of maxima within them, are also 
to be explained by motions of gaseous matter in the line of sight. 
Hence we conclude that the width and the displacements of corre- 
sponding maxima should be linear functions of the wave-lengths, 
but independent of the chemical nature of the emitting substances. 
The correctness of this conclusion is shown in the following table. 
Here the measurements given in the second column refer to the chief 
(violet) maximum of the bright bands, while the displacements in 
the third column have been computed from the formula 
- c£A. = 0 00212 x X. 
The fourth column contains the observed widths of the bright 
bands. Naturally these measurements are far less reliable, but 
nevertheless the alleged proportionality to the wave-length is quite 
evident. 
Displacement of chief maximum 
of bright bands 
Wave-length. 
Obs. 
Comp. 
Width. 
3868*9 t.m. 
- 8‘7 t.m. 
- 8’2 t.m. 
31 
3967*6 
-8-6 
-8'4 
31 
4101-9 H 
-8-2 
-8-7 
36 
4340 6 H 
-9-4 
- 9-1 
4363*3 Neb. 
-9-7 
-9-2 
33 
4471-6 He 
-9-6 
-9-5 
34 
4643- 
-11 
-10 
4685-9 Neb. 
- 10 
- 10 
4713-2 He 
- 10 
- 10 
4861*5 H 
-9 
- 10 
33 
4959-0 Neb. 
-11 
- 11 
34 
5007-0 Neb 
-11 
-11 
38 
5752- Neb. 
-11 
-12 
43 
5875-9 He 
-13 
-13 
40 
