326 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



spots, is sufficiently well sliowu, as well as a dark flocculus wliich developed 

 southeast of the smaller spot. * * * 



If we call C the point of nearest approach of this flocculus to the spot, we 

 have the following results of measurements : Between exposures 6 and 7 we 

 find for the point C a change of 1.9° in latitude and 1.5° in longitude. This 

 corresponds to a motion of 2.4° in 195 seconds, or 177 kilometers per second. 

 Between exposures 7 and 9, in an interval of 408 seconds, there was a change of 

 3° in latitude and 0.4° in longitude, giving a velocity of 89 kilometers per sec- 

 ond. Eight minutes later '^ the extension had divided and moved nearly to the 

 spots, the resultant motion for each extremity being 2.8°, giving a velocity of 

 71 kilometers per second. * * * 



The difl'erences among the three velocities can not be trusted, though the evi- 

 dence favors the view that the first velocity was actually higher than the others. 

 The mean of the six measures (106 kilometers) will at least sei've to give the 

 order of the maximum velocity in the vortex. 



The appearance of the spot and surrounding region thirteen hours after the 

 rapid changes described above is shown in figure 2, plate 3. The straight radial 

 lines in this photograph are in marked contrast to the curved structure pre- 

 viously shown. The eastern of the more plainly marked radial lines is found by 

 measurement to be a short distance to the east of the extension from the large 

 flocculus to the spots shovni in figure 2, plate 3. The forked connection to the 

 two spots has disappeared and a strong dark flocculus has developed at the 

 southei'n extermity of the radial line, mainly on its eastern side. In the photo- 

 graph of June 5, 7'' 05'" a. m. (No. 4220), the radial structure surrounding the 

 spots is greatly altered and the flocculus, no longer recognizable, has developed 

 a large extension toward the west. A notable feature of this photograph is the 

 amount of bright eruptive hydrogen in the region surrounding the two spots. 

 Some eruptive matter also appears in the photographs of the preceding day, but 

 here it is greatly augmented. * * * 



As already remarked, the distance from the spot of the western extermity of 

 the large flocculus did not vary systematically. The eastern extremity, on the 

 contrary, commenced on June 1 to approach the spot, and continued to do so 

 until the sudden change occurred on June 3. Up to this time the velocity, 

 instead of showing signs of acceleration, was apparently retarded, but the chang- 

 ing form of the flocculus leaves this point uncertain. On the photograph of 

 May 29 (No. 4176) the whirl is most conspicuous north of the spot, where its 

 extreme distance is about equal to that of the western end of the large floc- 

 culus. Apparently, however, the flocculus did not fall completely under the 

 influence of the vortex until June 1, when its eastern extremity was 11.4° = 

 140,000 kilometers from the spot. The fact that the minimum distance of the 

 western end always exceeded this quantity may account for its escape. * * * 



It may be well to direct attention to certain points which have I)een noted: 



In the series of photographs (on negatives Nos. 4201 and 4202) which show 

 the large flocculus in the act of being drawn into the spots, the small flocculi 

 near the spots remain almost unchanged in position, perhaps because of differ- 

 ence of level. 



Except in the case of the large flocculus, attempts to detect evidences of 

 motion toward the spots have not yet proved successful, even along apparent 

 lines of flow. 



Negative No. 4196, taken on June 2, shows a dark cometlike object (appar- 

 ently defining a line of flow) intersecting a bright eruptive flocculus. The 

 appearance suggests that the eruption does not rise to the level of the vortex. 



« The time of negative No. 4202 is recorded only to the nearest minute. 



