Progress of Astronomy during the Year 1879. 447 
become thereby raised to a state of more vivid incandescence. 
The spectrum of a ray which, coming from the photosphere, reaches 
this zone, would exhibit the lines of oxygen and hydrogen dark, 
but those of the former much fainter than those of the latter, the 
specific absorptive power of hydrogen at a given temperature 
being much greater than that of oxygen. The action of the 
incandescent gases of the zone of combustion on such a spectrum 
would be to reverse the oxygen lines, and weaken the hydrogen 
lines. The temperature of the coronal regions being much lower, 
any oxygen existing in it would be in the state of molecular 
agoregation corresponding to the compound spectrum, and would 
thus be without influence on the bright lines, but would give rise 
to the dark lines of the compound spectrum. 
Professor Tacchini states that he saw the corona in full day- 
light, on July 29, 1878, at Palermo, the sky being of exceptional 
transparency. By hiding the disc of the sun he was able to make 
a drawing of the corona, which agrees well with one made by 
Father Sestini, in America, on the same day, during the eclipse. 
The rays were, on one side, traced more than a degree from the 
centre of the sun. Prof. Langley and Mr. Brett have also seen 
the corona in full sunlight.* 
A very elaborate paper on the polarisation of the corona, by 
Dr. Schuster, is published in the M.N. for December. It is im- 
possible here to give an abstract of this paper, in which is shown 
how combined measures of the polarisation at different distances 
from the sun, and of the decrease in intensity of the total light of 
the corona with increasing distance from the sun, may inform us 
in what way the scattering matter is distributed in the solar 
atmosphere, what part of the light sent out by the corona is due 
to scattering matter, and whether the lattev is projected outwards 
from, or is falling into the sun from outside. 
While the United States Naval Observatory is printing a very 
full account of the work done by the expeditions sent out under 
its auspices to observe the eclipse of July 28, 1878, Mr. Leonard 
Waldo has published a report on the observations made at Fort 
Worth, Texas, by a party of which he was the leading member.+ 
* [For some earlier views of the corona in daylight by Tacchini, see Secchi, ‘‘ Le Soleil,’ 
German edition, p. 350-52. } 
t Cambridge, Mass. (J. Wilson aud Son.) 1879, 4to. 
