OF ArOUST 28 TO SEPTEMBEE 7, 1859. 
427 
attached to the object-glass, by which the general image is thrown into shade, for the 
brilliancy was fully equal to that of direct sunlight ; but, by at once interrupting the 
current obsenntion, and causing the image to move by turning the R.A. handle, I 
saw I was an unprepared witness of a very ditferent affair. I thereupon noted down 
the time by the chronometer, and, seeing the outburst to be very rapidly on the 
increase, and being somewhat flurried by the surprise, I hastily ran to call some one 
to witness the exhibition with me, and on returning within 60 seconds, was mortified 
to find that it was already much changed and enfeebled. Very shortly afterwards the 
last trace was gone; and although I maintained a strict watch for nearly an hour, 
no recurrence took place. The last traces were at C and D, the patches having 
travelled considerably from their first position, and vanishing as two rapidly fading 
dots of white light. The instant of the first outburst was not 15 seconds different 
from 11*' 18™ Greenwich mean time, and 11'’ 23™ was taken for the time of disap- 
pearance. In tliis lapse of five minutes, the two patches of light traversed a space of 
about 35,000 miles, as may be seen by the diagram, which is given exactly on a scale 
of 12 inches to the sun’s diameter. On this scale the section of the earth will be very 
nearly equal in area to that of the detached spot situated most to the north in the 
diagram, and the section of .Jupiter would about cover the area of the larger group, 
without including the outlying portions. It was impossible, on first witnessing an 
appearance so similar to a sudden conflagration, not to expect a considerable result in 
the way of alteration of the details of the group in which it occurred; and I was 
certainly surprised, on referring to the sketch which I had carefully and satisfactorily 
(and I may add fortunately) finished before the occurrence, at finding myself unable to 
recognize any change whatever as having taken place. The impression left upon me is, 
that the phenomenon took place at an elevation considerably above the general surface 
of the sun, and, accordingly, altogether above and over the great group in which it was 
seen projected. Both in figure and position the patches of liglit seemed entirely inde- 
pendent of the configuration of the great spot, and of its parts, whether nucleus or 
umbra. The customary observation was shortly resumed ; and the diagram engraved. 
