CELESTIAL SPECTROSCOPY, 79 
tricity, the rays being lines of force, and the coronal matter discharged 
from the sun, or at least arranged or controlled by these forces. At 
the extremities of the streams for some reasons the repulsive power may 
be lost, and gravitation set in, bringing the matter back to the sun. 
The matter which does leave the sun is persistently transported to the 
equatorial plane of the corona; in fact, the zodiacal light may be the 
accumulation at great distances from the sun along this equator of such 
like material. Photographs on a larger scale will be desirable for the 
full development of the conclusions which may follow from this study 
of the curved forms of the coronal structure. Prof. Schaeberle, how- 
ever, considers that the coronal phenomena may be satisfactorily ac- 
counted for on the supposition that the corona is formed of streams of 
matter ejected mainly from the spot zones with great initial velocities, 
but smaller than 382 miles per second. Further, that the different types 
of the corona are due to the effects of perspective on the streams, from 
the earth’s place at the time relatively to the plane of the solar equator. 
Of the physical and the chemical nature of the coronal matter we 
know very little. Schuster concludes, from an examination of the 
eclipses of 1582, 1883, and 1886, that the continuous spectrum of the 
corona has the maximum of actinic intensity displaced considerably 
towards the red when compared with the spectrum of the sun, which 
shows that it can only be due in small part to solar light scattered by 
small particles. The lines of calcium and of hydrogen do not appear to 
form part of the normal spectrum of the corona. The green coronal 
line has no known representative in terrestrial substances, nor has 
Schuster been able to recognize any of our elements in the other lines 
of the corona. 
Stellar evolution.—The spectra of the stars are almost infinitely 
(liversified, yet they can be arranged with some exceptions in a series 
in which the adjacent spectra, especially in the photographic region, 
are scarcely distinguishable, passing from the bluish-white stars like 
Sirius, through stars more or less solar in character, to stars with 
banded spectra, which divide themselves into two apparently inde- 
pendent groups, according as the stronger edge of the bands is towards 
the red or the blue. Insuch an arrangement the sun’s place is towards 
the middle of the series. 
At present a difference of opinion exists as to the direction in the 
series in which evolution is proceeding, whether by further condensa- 
tion white stars pass into the orange and red stages, or whether these 
more colored stars are younger and will become white by increasing 
age. The latter view was suggested by Johnstone Stoney in 1867. 
About ten years ago Ritter in a series of papers discussed the behav- 
lor of gaseous masses during condensation, and the probable resulting 
constitution of the heavenly bodies. According to him, a star passes 
through the orange and red stages twice, first during a comparatively 
