SCIENTIFIC SUMMARY. 
ASTRONOMY". 
~TiISCOVERY of Oxygen in the Sun . — Three interesting astronomical dis- 
coveries have been made during the past q uarter. Undoubtedly the most 
important of these is the discovery of oxygen in the sun, by Dr. H. Draper, 
of New Y T ork. Although in some respects the discovery may be regarded 
as belonging rather to physics than to astronomy, yet its relation to the 
chief of all the bodies with which astronomy has to deal is too close to 
permit us to regard it as otherwise than astronomical. 
Dr. Draper, who has been engaged now for several years in applying pho- 
tography to che celestial bodies and their spectra (see our summary of astro- 
nomy for April last), in comparing the part of the solar spectrum between 
the lines Gr and II with the spectrum of air, finds that the oxygen lines 
are represented in the solar spectrum by bright lines. A well-marked 
quadruple oxygen line between wave lengths 4,345 and 4,350 coincides 
exactly with a bright group in the solar spectrum. This oxygen group 
alone is almost sufficient to prove the presence of oxygen in the sun, for 
not only does each of the four components have a representative in the solar 
spectrum, but the relative strength and the general aspect of the lines in 
each case is similar. On this point Dr. Draper remarks that he does not 
think sufficient stress has been laid on the general appearance of lines apart 
from their mere position ; in photographic representations this point is very 
prominent. Several other coincidences are noted, leaving no room for doubt 
that oxygen exists in the sun in such a condition that its lines appear 
bright in the solar spectrum instead of dark like the lines of sodium, of 
iron, &c., and (usually) of hydrogen. As to the existence of nitrogen 
in the sun, there is not yet certainty. “ Nevertheless,” says Dr. Draper, 
iC even by comparing the diffused nitrogen lines of the particular photo- 
graph ” selected for showing the oxygen coincidences, “ in which nitrogen 
has been sacrificed to get the best effect for oxygen, the character of the 
evidence appears. The triple band between 4,240, 4,227, if traced upward 
into the sun, has approximate representatives. Again, at 4,041 the same 
thing is seen, the solar bright line being especially marked. In another pho- 
tograph the heavy line at 3,995, which in this picture is opposite an insuffi- 
ciently exposed part of the solar spectrum, shows a comparison band in the 
sun.” The bright lines of oxygen in the solar spectrum have not hitherto 
been perceived, probably from the fact that in eye observation bright lines 
on a less bright ground do not make the same impression on the mind as 
