C. S. Hastings— Constitution of the Sun. 33 
Art. IIl—A Theory of the Constitution of the Sun, founded upon 
Spectroscopic Observations, original and other; by CHARLES 
S. Hasrines. 
FRAUNHOFER discovered the lines in the solar spectrum, 
known by his name, in 1814. Many efforts to determine their 
origin followed. One of the most ingenious and carefully 
considered was that of Professor Forbes in 1836.* He con- 
cluded that, if their origin is in the solar atmosphere, the light 
from the limb must exhibit stronger lines than that from the 
center. His method was to examine the spectrum before and 
during an annular eclipse; as he found no recognizable change, 
his deduction was, “that the sun’s atmosphere has nothing to 
do with the production of this singular phenomenon.” 
The point was again touched upon by Sir David Brewster 
and Dr. Gladstone in a joint study of the spectral lines, pub- 
lished in 1860.+ Here “each of the authors came independ- 
ently to the conclusion that there is no perceptible difference 
in this respect between the light from the edge and that from 
the center of the solar disk.” 
In 1867 Angstrémt repeated the experiment with negative 
results. Lockyer’s| efforts also, in 1869, were attended with 
no better results. 
In 1873, four years later, I devised and made an apparatus 
by which a perfect juxtaposition of the spectra of the center 
and limb was secured. his apparatus and certain of the re- 
Sults gained by its use were described in a note “ On a com- 
parison of the Spectra of the limb and the center of the Sun,” 
published in this Journal, vol. v (1878), pp. 869-371. I was 
then a student at Yale College and soon after left New Haven, 
when the research was necessarily interrupted. I hoped, how- 
ihe that the novelty and interest of the observations might 
othe 
the same as that described in the article cited ; instead, how- 
ever, of the equatorial of the Sheffield Scientific School, I 
used a Clark equatorial of 9-4 in. aperture and 120 in. focal 
* Notes relative to the supposed Origin of the Deficient Rays in the Solar Spec- 
trum. Phil. Trans., 1836, pp. 453-456. 
On the Lines of the Solar Spectrum. Phil. Trans., 1860, pp. 149-161. 
Phil. Mag., 1867, p. 76. Proc. R. &., vol. xvii, p. 350. 
Am. Jour. gato Serizs, Vou. XXI, No, 121.—Jan., 1881. 
