ASTRONOMY: HALE AND ELLERMAN 
107 
bral filaments extend toward the umbra of a sun-spot in Langley's draw- 
ing. On either side of this axis, as defined by the long dark flocculus 
(here bright) which appeared later as a prominence at the sun's limb, 
they stop abruptly at the edge of a region of honeycomb structure, out of 
which the long prominence rises like a high ridge. This prominence is 
shown by the original negatives to be composed of slender filaments, in 
some parts parallel for long distances, in others apparently intertwined. 
At its western (right-hand) extremity the prominence curves sharply in 
a clockwise direction toward the upper spot near the western end of the 
group (fig. 1), indicated at this level only by a minute white dot, much 
smaller than the direct image. The extreme western spot, though per- 
haps the largest in the group, is partially obscured in figure 5, though 
the hydrogen flocculi may be seen curving toward it. The neighboring 
spot to the east, however, is plainly visible, and its effect upon the long 
ridge-like prominence is shown by a second clockwise twist. 
The next large spot in the group is clearly seen in the stereoscope, 
but its smaller companions to the east are obscured by the extensive 
bright hydrogen flocculi which cover much of the central part of the 
image, producing the apparently dark background near the middle of 
the negative print. It should be added that the three large spots just 
mentioned were shown by spectroscopic observations to be of the same 
magnetic polarity, indicating that their vortices were rotating in the 
same direction. This is in harmony with the clockwise curvature of the 
hydrogen flocculi shown by the stereoscope to be flowing toward each 
of the spots. 
Further to the west (above the center of fig. 1), is a bipolar spot-group, 
over which the hydrogen vortex is beautifully shown in figure 5 for the 
western (clockwise) member of the group, though the vortex above the 
eastern spot is less obvious. The crater-like depression at the center 
of the western vortex is plainly visible in the stereoscope, which also 
brings out the bright (dark in fig. 5) star-like boundary surrounding this 
member of the pair. The magnetic polarity of this spot was the same as 
that of the three already mentioned. 
The two eastern spots near the lower left corner of figure 1 form 
another bipolar group, but both are partially or wholly obscured in figure 
5, and the vortex structure about them is not well defined. At this 
end of the long ridge-like prominence some divergent filaments rise to a 
considerable height. These present a remarkable wave-like form in 
spectrohehograms taken on August 9. It is interesting to note that 
the highest parts of the prominence and all of the other high level 
phenomena are dark (bright in fig. 5), as would be expected on the 
