m 



72 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1913. 



The question was next taken up whether the distribution of spots 

 in longitude did not become more unequal when the three planets 

 considered, or two of them, were in conjunction for the same solar 

 zone. The plots were remade considering only the spots born when 

 that condition was fulfilled. No marked difference was evident. It 

 seems as if the number of spots appearing in a zone is greater onlj^ 

 when one of the planets in the conjunction, or slightly past it, is 

 Venus. Schuster thinks that a planet may have merely an exciting 

 action, effective only in putting into play a force already existing 

 in the sun. Accordingly, a second planet on conjunction might not 

 have any additional effect. 



RESEARCHES OF F. J. M. STRATTON. 



Stratton (Monthly Notices, 72, p. 9, 1911) thought that it would be 

 worth while to again take up this research, considering the disap- 

 pearances as well as the appearances, and retaining only those which 

 occur at less than 50 degrees from the solar meridian passing through 

 the earth. He considers only Jupiter and Venus, which seemed the 

 most probable as having an influence on the spottedness. The 

 period used was the one of 36 years, 1874 to 1909, for which the 

 photographs of the Greenwich Observatory furnished a complete 

 series. 



The surface of the sun was divided into 24 equal zones instead of 

 the 12 which Schuster used. The origin was the meridian passing 

 through the planet at the moment of birth or disappearance of a 

 spot. The zones to 6 corresponded to meridians which had 

 already passed over the planet but which are now hid from it. The 

 zones 18 to 24 corresponded to meridians which are to transit but 

 which are still out of sight. 



He then constructed for each planet plots in which the abscissae 

 were the zone numbers and the orclinates — 



(a) The number of spots seen for the first time in each zone. 



(h) The number of spots seen for the first time in the northern 

 part of each zone. 



(c) The number of spots seen for the first time in the southern 

 part of each zone. 



(d) The number of ephemeral (that is, seen for one day only) 

 spots seen in each zone. 



(e) Total number of spots seen either for the first time or for one 

 day only in each zone. 



This gave five curves for each planet. These were remade, using 

 the spots seen for the last time instead of those seen for the first time; 

 that is, disappearances instead of appearances. 



