THE SWS COKOA'A AND HIS SPOTS. 5 



dition of the sun with regard to spots in 1605 ; but we 

 know that the year 1615 was one of many spots, and the 

 year 1610 one of few spots; whence we may conclude 

 safely that the year 1605 was one of many spots. This 

 case then is in favour of the theory we are examining. 



In passing we may ask whether the observation by 

 Clavius which had perplexed Kepler, may not throw some 

 light on our subject. Clavius says that the eclipse of 1567 

 which should have been total was annular. The usual 

 explanation of this has been that the corona was intensely 

 bright close to the sun. And though Kepler considered 

 that his own observation of a broad reddish corona satis- 

 factorily removed Clavius's difficulty, it seems tolerably clear 

 that the corona seen by Clavius must have been very 

 unlike the corona seen by Kepler. In fact the former must 

 have been like the corona seen in July, 1878, much smaller 

 than the average, but correspondingly increased in lustre. 

 Now with regard to the sun-spot period we can go back to 

 the year 1567, though not quite so securely as we could 

 wish. Taking the average sun-spot period at eleven years, 

 and calculating back from the minimum of spots in the 

 year 1610, we get four years of minimum solar disturbance, 

 1599, 1588, 1577, and 1566. Weshould have obtained the 

 same result if we had used the more exact period, eleven one- 

 ninth years, and had taken 1610-8 for the epoch of least 

 solar disturbance (1610-8 meaning about the middle of 

 October, 1610). Thus the year 1567 was a year of few sun- 

 spots, probably occupying almost exactly the same position 

 in the sun-spot period as the year 1878. Clavius's obser- 

 vation, then, is in favour of our theory. 



But another observation between Clavius's and Kepler's 

 may here be noticed. Jensenius, who observed the eclipse 

 of 1598 at Torgau in Germany, noticed that, at the time of 

 mid-totality, a bright light shone round the moon. On this 

 occasion, remarks Grant, the phenomenon was generally 

 supposed to arise from a defect in the totality of the eclipse, 

 though Kepler strenuously contended that such an explana- 



