468 Scientific Intelligence. 
Many other observations of auroral spectra have been made, but 
in most cases the lines were not measured even approximately. 
G. F. B. 
2. An Explosion on the Sun; by C. A. Youne. (Boston Jour- 
nal of Chemistry).—On the 7th of September, between half past 
twelve and two Pp. M., there occurred an outburst of solar energy 
remarkable for its suddenness and violence. Just at noon the 
riter had 
at the sun’s distance 1” equals 450 miles nearly, it was about 
100,000 miles long by 54,000 high. 
At 12°30", when I was called away for a few minutes, there was 
no indication of what was about to happen, except that one of 
the connecting stems at the southern extremity of the cloud had 
grown considerably brighter, and was curiously bent to one side ; 
and near the base of another at the northern end a little brilliant 
lump had developed itself, shaped much like a summer thund 
ead. Figure 1 represents the prominence at this time, @ berg 
the little “thunder-head.”t 
was my surprise, then, on returning in less than half = 
hour (at 12"55™), to find that in the meantime the whole thing ha 
been literally blown to shreds by some inconceivable up-rush from 
* This is the name given by Schellen to the combination of astronomical tele- 
scope and spectroscope. f 
+ The chromosphere (called also sierra by Proctor and others) is the layer a 
ye mn and other gases which surrounds the sun to a depth of about 7,0! 
miles. Of this the prominences are mere extensions. “2e 
7 The sketches do not pretend to accuracy of detail, except the 4th; the thr 
rolls in that are nearly exact. 
