446 Sir Norman Lockyer and Dr. W. J. S. Lockyer. [Mar. 17, 



" Solar Prominence and Spot Circulation, 1872 — 1901." By Sir 

 Norman Lockyer, K.C.B., F.K.S., and William J. S. Lockyer, 

 Chief Assistant, Solar Physics Observatory, M.A. (Camb.), 

 Ph.D. (Gott.), F.E.A.S. Received March 17,— Bead March 26, 

 1903. 



[Plates 6 A5?d 7.] 



In oivr former communications* referring to the connection between 

 solar, meteorological, and magnetic changes, some of the results 

 obtained by the reduction of the solar prominences, as observed by 

 Professor Tacchini at Eome, were described. It was stated that the 

 curve representing the variation of percentage frequency of the 

 prominences for the whole limb of the sun indicated that in addition 

 to the main epochs of maxima and minima coinciding in time generally 

 with those of the maxima and minima of the total spotted area, there 

 were also prominent subsidiary maxima and minima. 



Further, dividing the sun's limb into zones of 20° in width from the 

 equator, with a polar zone of 10 3 , and dicussing each zone separately, 

 the variation of the prominence percentage frequency about the 

 equator was found to be very different from that in the higher lati- 

 tudes, the former changing with the spots, and the latter exhibiting 

 sudden outbursts just previous to the epochs of sunspot maxima, 

 followed and preceded by comparatively long intervals of quietude. 



In the present communication, the prominence observations have 

 been discussed from a different point of view, in order to trace out, if 

 possible, the heliographic latitudes of the chief centres of action of 

 prominence disturbance. In this way it could be determined whether 

 such movements are subject to some periodic law, in which case it 

 would be possible to increase our knowledge of the circulation of the 

 solar atmosphere in regions outside those in which sunspots alone have, 

 up to the present, been employed. 



The changes of latitude of the zones which contain the centres of 

 sunspot disturbances were first pointed out by Carrington,f whose fine 

 series of observations led him to discover " a greater contraction of 

 the limiting parallels between which spots were formed for the two 

 years previous to the minimum of 1856, and soon after this epoch the 

 apparent commencement of two fresh belts of spots in higher latitudes 

 north and south, which have in subsequent years shown a tendency to 

 coalesce, and ultimately to contract as before to extinction." 



The study of the subject was taken up later by Spoerer,| who 



* ' Roy. Soc. Proc.,' vol. 70, p. 502; vol. 71, pp. 134 and 244. 

 f ' Observations of the Spots on the Sun from Not ember 9, 1853, to March 24, 

 1861, made at Eedhill,' p. 17. 



X ' Beobachtungen der Sonnennecken von Oct., 1871 — Dec, 1873, und von Jan., 



