130 



KNOWLEDGE, 



[June, 1903. 



researches of Kaptovu suggest that there is a prejiouderance 

 of metallic stars among the stars nearest to us, but at the 

 same time there are many stars of this class wliich have no 

 ai)precialile proper motion, and are therefore presumably 

 among the stars most remote. It may therefore he 

 concUuled that matter similar io that composing the sun 

 is distributed throughout the visible universe. 



THE SUNSPOTSOF 1903, MARCH AND APRIL. 



By E. Walter Maundkr, f.e.a.s. 



The year 1901 was, beyond question, the year of the solar 

 minimum. But the evidences of reviving activity were 

 curiously slow to manifest themselves. There was, indeed, 

 a slight upward progression in UH)-2, the mean daily 

 spotted area being nearly double what it had been in the 

 previous year. But the intervals during which the solar 

 disk remained absolutely quiescent were numerous and 

 long, so that whereas 81 per cent, of the days in 1901 

 showed no spots, 72 per cent, in 1902 were in a like case. 

 From 1902, June 5, to September 17, a period of fifteen 

 weeks, there was practically unbroken quiescence; only 

 two or three minute spots — and these faint and sliort- 

 lived — were seen during the whole time. But with 

 September 18 a more active period began, and the next 

 ten weeks showed more spot groups than the whole of the 

 year l)eside. December was a quiet month, but new 



Group A, 1903, Slarcli 2(1 



spots were seen with the commencement' of the new year, 

 and the sun showed a slight but steady activity up to 

 March 21. 



On this day a distinctly new phase commenced. A 

 large regular spot, which for distinctness of reference 

 we will call A, appeared on the east limli, in north 

 latitude 24*-\ Two days later another group appeared, 

 likewise at the east limb and in the same latitude. This 

 second group, B, consisted of a small stream of rather 

 unstable spots. On March 26th a third group, C, appeared 

 also on the east limb. This spot was larger than its 

 predecessors, but was apparently in a later stage of 

 development. The areas covered by these three groups, if 

 expressed in the unit adopted at the Royal Observatory, 

 (Treenwich, '• millionths of the sun's visible hemisphere," 

 would be about 200, 100, and 260. The Greenwich unit 

 (■(irresp(mds to a little more than a millicm square miles, 

 si> that the areas expressed as millions of square miles 

 would be approximately 240, 120, and 300. 



These areas ai-e, of course, quite small com])ared with 

 those which are presented to us at the time cf the solar 

 niaxiiuum. Thus ou 1893, August 7th, the total area 

 I'overed by all the spots visible on that day amounted to 



fiOOO millions of square miles ; that is to say, an area nine 

 times as great as that presented by the combination of 

 these three groups. Indeed, one of the groups of the 

 minimum year. 1901, was as large as these three groups 

 put toyvflicr ; yi'ttlie sun has been so quiet for so long 

 that cousidi'iMl.].' attention has been attracted by them, 

 not ni('r( ly in scieutific quarters but also in the daily press. 

 By April 3rd, the first group. A, had passed off at the 

 west limb ; the second group, B, which had disapyieared 

 for a while and then formed afresh on a somewliat larger 



Group C, 1903, Mnrcli HI. 



scale, was a])proa(;hiug the west limb ; and the third, C, 

 which was in latitude 17^ S., had liroken up and greatly 

 diminished, and only two small faint spots remained. As 

 if to compensate for this diminution, a fourth group, D, 

 appeared on this day on the east limb in the same latitude, 

 or nearly so, as group C. Group D was larger tlian 

 any of its predecessors, and was fairly regular in shape, 

 with a fringe of small sjjots bordering it on the following 

 side. Its area was about 420 millions of square miles. 



A particular interest attached to this group D, in that 

 when it had advanced rather more than halfway towards 

 the central meridian there was a sharply marked little 

 magnetic disturbance, which may or may not have been 

 connected with it. It is certainly not one of the instances 



Group D, 1903, April G. 



in which the connection Ijetween sunspot and niagnelic 

 disturbance is unmistakable, but it deserves note as an 

 instance of possible connection. 



On April 8th, a small stream of faint spots, E, appeared 

 on the east liml) in latitude 22^ N. Ou April 19th, two 

 groujis, both small, apjieared on the east limb, the one 

 a return of the spot A of March 21st, and the other, P, 

 almost balancing it in the southern hemisphere. That is 

 to say, the two spots had nearly the same longitude, but 

 their latitudes were of opposite signs. Spot C of March 

 26th returned ou April 2:?nd. On April 24th a new group 



