SOLAR VOETICES AND MAGNETISM IN SUN SPOTS ABBOT. 325 



appears on the former plate southeast of the spot continues, but is changed in 

 form and less brilliant than before. A strong eruption of peculiar form appears 

 southwest of the spot, and bright hydrogen to the northeast. Strong, dark 

 tlocculi have also developed at many points around the spot. The eastern end 

 of the long, dark flocculus is still changing, and a projection appears vilest of 

 its center (see plate 1). A negative taken on the same day at 5*" 13"" p. m. No. 

 417S) shows further changes in both bright and dark structure, especially' in 

 the region southwest of the spot. A fork has developed in the western end of 

 the long dark flocculus, and a small but very dark flocculus appears just west 

 of the spot. Another photograph (No. 417;*), the first exposure of which was 

 made at 5" 26"" p. m., shows a bright eruption west of the spot, where the small 

 dark flocculus appears on No. 4178. The eruption underwent considerable 

 change of form while the five exposures on this plate, separated by intervals 

 of a few minutes, were being made. At 6'' 04"" p. m. negative No. 4181 shows that 

 the eruption had subsided, and brings out other definite changes in structure 

 near the spot. The small dark flocculus has disappeared. On May 31, at 8" 09"' 

 a. m. (No. 4188), the fork at the western extremity of the long dark flocculus 

 has partially closed. No eruptions appear west of the spot, but there are bright 

 ones to the southeast. Other important changes are evident, and the two 

 bridges across the spot are conspicuous. On June 1, at 6'' 30™ a. m. (No. 4189), 

 the fork at tlie western end of the long dark flocculus appears more nearly 

 as it did in negative No. 4181, and the two bridges over the si)ot are very 

 marked. A negative taken flfteen minutes later (No. 4190) shows distinct 

 changes, especially in the region south and southeast of the spot. At S"" OS"' p. m. 

 of the same day negative 4193 shows a more distinct whirl near the spot, 

 and the long dark flocculus appears to be growing shorter at its eastern 

 end. On June 2, at 6^ 10™ a. m. (No. 4196), the whirling structure is very 

 marked and more nearly symmetrical about the spot, which is divided into 

 two parts (fig. 2, pi. 1). At 7'' 27"" a. m. (No. 4198) the whirl is also very 

 marked and somewhat changed in form. 



Up to tills time the changes, while in many cases rapid, were not especially 

 violent. On June 3, in an interval of about ten minutes, a remarkable trans- 

 formation occurred. The long dark flocculus, which had been gradually chang- 

 ing in form and position, was suddenly drawn into the spot. As figure 2, plate 

 1, illustrates, the whirls were very conspicuous on the preceding day. A series 

 of photographs, nine of which were made on negative No. 4201. between 

 4'' 48"' 09^ p. m. and 5" 13"" 54^ p. m., and one, showing the entire disk, on nega- 

 tive No. 4202, at 5" 22"' p. m., records the changes which took place during this 

 time. These photographs were taken by Dr. C. E. St. John, who joined the ob- 

 servatory staff in May, and is sharing with me the observation work with the 

 five-foot spectroheliograph during Mr. Ellerman's absence on vacation. Three of 

 these have been selected for reproduction. Figure 1, plate 2, is enlarged from a 

 photograph made at 4" 58"' 16^ p. m. (time of transit of spot across collimator 

 slit of spectroheliograph). At 5" 01"' 21'' the large dark flocculus is appar- 

 ently unchanged in form. At 5'' 04" 21^ an exposure, which is not quite so well 

 deflned, gives no certain evidence of change. The next exposure, made at 5'' 07"* 

 06% clearly shows the development of a fork at the eastern end of the flocculus, 

 with traces of a very faint curved extension toward the larger spot. * * * 

 The nest exposure, made at 5" 10"' 52% shows the fork and part of the exten- 

 sion, but the definition is poor and the position of the end of the extension un- 

 certain. The last exposure on this plate, made at 5" 13'" 54^, is reproduced in 

 figure 2, plate 2. * * * The spot region on negative No. 4202, made at 5" 22'" 

 p. m. (time of transit of spot), is reproduced in figure 1, pl.'to 3. Here the 

 definition and contrast are also poor, but the extension reaching nearly to the 



