106 J. N. Lockyer on the supposed Compound 
In the sun, where it is as thick as H, the hydrogen lines 
have vastly thinned. 
While this paper has been in preparation, Dr. Huggins has 
been good enough to communicate to me the results of his 
most important observations, and I have also had an oppor: 
tunity of inspecting several of the photographs which he has 
recently taken. The result of the recent work has been to 
show that H and fare of about the same breadth in Sirius. 
In a Aquilz while the relation of H toh is not greatly changed, 
a distinct approach to the solar condition is observed, K being 
now unmistakably present, although its breadth is small as com- 
a with that of H. I must express my obligations to Dr. 
uggins for granting me permission to enrich my paper b' 
reference to these unpublished observations. His letter, which 
I have permission to quote, is as follows :— 
“Tt may be gratifying to you to learn that in a photograph 
I have recently taken of the spectrum of a Aquile there is 4 
line corresponding to the more refrangible of the solar H lines 
[that is K], but about half the breadth of the line correspond- 
ing to the first H lines. ‘ 
In the spectra of a Lyre and Sirius the second line is absent. 
K H 
Blue line. Red line. 
| Sirius. 
! | Sun. 
| : are. 
| Flame. 
Fig. 4.—The Molecular Groupings of Calcium. 
- Professor Young’s observations of the chromospheric line, t0 
which I shall afterward refer, give important evidence regarding 
the presence of calcium in the chromosphere of the sun. He 
finds that the H and K lines of calcium are aoonely reversed 
in every important spot, and that in solar storms H has been 
observed injected into the chromosphere seventy-five times, and 
K fifty times, while the blue line at W. L. 4226°, the all- 
important line at the arc-temperature, was only injected thrice. 
urther, in the eclipse observed in Siam in 1875, the H and 
K lines left the strongest record in the spectrum of the chromo 
sphere, while the line near G in a photographic hay of much 
greater intensity was not recorded at all. In the America? 
eclipse of the present year the H and K lines of calcium were 
distinctly visible at the base of the corona, in which for the 
time the observer could scarcely trace the existence of aDy 
