486 



SCIENCE 



[N. S. Vol. LI. No. 1324 



magnitude star. This refers to the blue light 

 which most affects the photo-electric cell, 

 which is not very different from the photo- 

 graphic plate in color sensitivity. 



Joel Stebbins 

 Universitt of Illinois Observatory 



the recent auroras and sun spots 

 The object of this preliminary communica- 

 tion is to call attention to the coincidence 

 with the recent magnetic displays of a huge 

 disturbance on the sun approximately parallel 

 to the Sim's equator and over 205,000 miles 

 long so situated that the whole of it approxi- 

 mately passed centrally requiring at least two 

 days for its passage over the sun's center. 

 The group of spots consisted of at least six 

 larger and numerous smaller ones, all string- 

 ing along in a line. My first observation of 

 it was on the 23d of March when most of 

 the group had already passed the center by 

 about a day. If the group existed prior to 

 the 23d without essential modification, it 

 began to pass the center between the 20th 

 and 21st, showing a lag in the propagation 

 from the sun to the earth, if there be such, of 

 something like two days. This seems to 

 favor Professor Snyder's recently announced 

 statement that there is a lag of 48 hours. 

 The observation seems at least to point to 

 the fact of there being some kind of proi)a- 

 gation. The central passage required about 

 two days and the aurora was evident on the 

 evenings of the 22d and 23d at least. 



Again on the 16th of April a medium-sized 

 spot became central. It was probably one of 

 the six siwts of the before mentioned group. 

 It was followed by a small siwt some 200,000 

 miles aftOT and also central about two days 

 later. It was possibly another remnant of 

 the old group, but too small to be of any 

 consequence. It had disappeared by the 19th. 

 Two or three days before the medium-sized 

 si)ot became central, I remarked to several of 

 my colleagues that I would not be surprised 

 at auroral display or at least magnetic dis- 

 turbances after it passed the center. I saw 

 no aurora, the sky was unfavorable, and prob- 

 ably also the time, but on the morning of the 



17th telegraph operators noticed a disturb- 

 ance, which must have been due to the alleged 

 propagation. If so the lag was about one day 

 in this case. 



My measurements of the positions of all 

 the spots were made on the sun's disc directly 

 with the micrometer and will yield helio- 

 graphic latitudes and longitudes of all the 

 points observed, but I have had no time to 

 make the computations. I would wish this 

 communication to be considered as a first 

 approximation to more accurate values. 



Syracuse University, 

 April 24, 1920 



E. D. EoE, Jr. 



POSSIBLE CONNECTION BETWEEN SUNSPOTS 

 AND EARTHQUAKES 



In Monthly Ifotices of the Royal Astronom- 

 ical Society for April, 1919, Professor H. H. 

 Turner has discussed data taken from the 

 Catalogue of Destructive Earthquakes com- 

 piled by Milne and from the Catalogue of 

 Chinese Earthquakes. He publishes tables of 

 earthquakes extending back to 49 a.d. and re- 

 fers to old Chinese records dating to 1820 B.C. 



From these da;ta he slightly modifies two sus- 

 pected earthquake periods, first published in 

 the Report of the Seismological Committee to 

 the British Association in 1912. The short 

 period is shown by him to have minor and 

 major limits of 14.8421 and 14.8448 months. 

 The long period is taken as seventy-eig'ht years. 

 His tables show these periods almost certainly 

 as real. 



Nine times the limits of the short period 

 give 11.1316 and 11.1336 years. Newcomb has 

 derived the sunspot period as 11.13 years and 

 Larmor and Yamaga as 11.125 years. The 

 chance that this close commensurability is acci- 

 dental is as the difference, which is less than 

 one one-hundredth of a year, is to the period 

 of about 1.24 years. That is about one in two 

 hundred and fifty. 



If the short period is so nearly commensur- 

 able the long period must be also. Seven times 

 the sunspot period is 77.91 years, agreeing to 

 0.09 years with his round figure of seventy- 

 eight years. 



