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quite certain that it is in great part subjective. On this view of the matter,, 
some of the observations seem more worthy than the rest of special notice. 
[Since the above lines were written, however, news has been received from 
Professor Young, of Princeton, America, which seems important. He- 
observed that the rice-grains close to the edge of Mercury seemed, if any- 
thing, lengthened radially. This was doubtless either an illusion or an 
accidental relation ; but as, if Mercury had an atmosphere of appreciable- 
breadth, the rice-grains would have been elongated the other way — that is, 
at right angles to the direction of radii of Mercury’s disc — we may safely 
infer that the atmosphere of Mercury is of very small depth. The bright 
and dusky rings must then be regarded as optical illusions.] 
Early Solar Photograph Showing Granules. — Dr. Rutherford, of New 
York, has presented to the Astronomical Society a copy on glass from a 
negative of the sun, made at his observatory on August 11, 1871. It repre- 
sents a small portion of the sun’s disc with one spot and a group of smaller 
ones. He calls attention to the fact that with a proper lens the granulations, 
rice-grains, or willow-leaves are quite clearly visible. M. Janssen was there- 
fore mistaken when he asserted that his photographs are the only ones, and 
the first, which show the granulations on the sun’s surface, though Dr. 
Rutherford admits freely the superiority of M. Janssen’s recent solar 
photographs. 
Oxygen Lines in the Sun. — Mr. Christie has made observations upon tho 
solar spectrum near the G line, which appear to throw some degree of doubt 
on the supposed evidence for the existence of oxygen in the sun obtained by 
Dr. H. Draper. When this region was examined with high dispersion the 
bright lines seemed much broader than the dark ones, and did not seem 
softened off either edge, as might be expected if they really were bright 
lines, and not parts of the continuous spectrum cut out or left by dark lines. 
He also found certain dark lines towards the middle of each of the bright 
bands or spaces. This he considers renders the hypothesis that the bright 
bands are really bright lines still more difficult, “as one would have to 
assume that the oxygen lines were each double, and were only separated by 
a very fine sharply defined interspace.” The latter inference is not valid,, 
however, for there is no reason why dark absorption lines should not be seen 
on the broad bands of the spectrum of oxygen. We know even that dark 
lines are usually seen on the bright bands of these elements, which increase 
the complexity of the spectrum by widening their lines. This is caused by 
the absorption of the rarer and cooler vapour of these same elements, lying 
outside the inferior hotter vapour. This part of the evidence is in favour of' 
the existence of bright bands, as distinguished from mere spaces between 
dark lines. Whether the other point may not be similarly explained, — that 
is, the sharply defined edges of the broad bands accounted for by the action 
of absorption vapours lying above the layers of oxygen giving the bright 
bands, — remains yet to be seen. The idea advanced by Dr. Schuster that 
oxygen is not probably present in the sun in both the forms whose spectra 
have been obtained in terrestrial experiments, seems to have very little in its 
favour. On the whole it does not yet appear that the very strong evidence 
advanced by Dr. Draper in favour of the existence of oxygen in the sun has 
been materially shaken. It would, however, be rash to speak at all positively- 
at the present stage of the inquiry. 
