308 W. Crookes—Spectrum of Helium. 
intensities of lines in one picture not being the same as those 
in another picture. Judgment is needed in deciding whether 
a line is to have an intensity of 7 or 8 assigned to it; and asin 
the tables I have not included lines below intensity 8, it might 
happen that another series of photographs with independent 
measurements of intensities would in some degree alter the 
above arrangement. 
In the following table I have given a list of lines which are 
probably identical with lines observed in the chromosphere and 
prominences : 
Wave-length Wave-lengths of 
observed of Intensities. chromospheric lines,* 
helium. Rowland’s scale. 
7065°5 10 - 7065°5 
6678°1 10 6678°3 
5876°0 30 5876°0 
5015°6 6 5015°9 
4922°6 10 4922°3 
4870°6 3 |  4870°4 
4847°3 7 4848°7 
4805°6 9 4805°25 
4713°4 9 A713°4 
4559°4 2 4558°9 
4520°9 3 4522°9 
AAT1°5 10 4471°8 
4437°1 if 4437°2 
4428°1 10 4426°6 
4424°0 10 4425°6 
4399°0 10 4398°9 
4386°3 6 4385°4 
4298°7 6 4298°5 
4227°1 5 4226°89 
4178°1 it 4179°5 
3964°8 10 3964:0 Bee 
3948°2 10 3945°2 H. 
3913°2 + 3915 Sule 
3888°'5 10 3888°73 H. 
3819°4 10 3819°8 D. 
813275 5 3733°3 
3705°4 6 3705°9 D. 
* A Treatise on Astronomical Spectroscopy, by Dr. J. Scheiner, translated by 
E. B. Frost, Boston, 1894. ~ 
+ The wave-lengths to which the initials D. and H. are added are wave-lengths 
of lines photographically detected in the spectrum of the chromosphere by Des- 
landres (D) and Hale (H). Their photographs do not extend beyond wave-length 
3630. Professor Lockyer (Roy. Soc. Proc., vol. Iviii, p. 116, May, 1895) has 
already pointed out fourteen coincidences between the wave-lengths of lines in 
terrestrial helium and in those observed in the chromosphere, the eclipse lines, 
and stellar spectra. 
