THE SUN'S CORONA AND HIS SPOTS. 9 



a case in which the evidence is plainly against the theory 

 we are examining, we must give up the theory at once. 

 For one case of d scordance does more to destroy a theory 

 respecting association between such and such phenomena, 

 than a hundred cases of agreement would do in the way of 

 continuing it. 



In 1724, Maraldi noticed that the corona was broadest 

 first on the side towards which the moon was advancing, 

 and afterwards on the side which the moon was leaving. 

 From this we may infer that the corona was only a narrow 

 ring on that occasion, since otherwise the slight difference 

 of breadth due to the moon's eccentric position at the 

 beginning and end of totality would not have been notice- 

 able. Now, the year 1723 was one of minimum disturbance, 

 with one year of doubt either way. Thus 1724 was cer- 

 tainly a year of few sun-spots, and may have been the 

 actual year of minimum disturbance. The corona then 

 presented an appearance according with the theory we are 

 considering. 



Few eclipses have been better observed than that of the 

 year 1733. The Royal Society of Sweden invited all who 

 could spare the time to assist, as far as their ability per- 

 mitted, in recording the phenomena presented during totality. 

 The pastor of Stona Malm states that at Catherines- 

 holm, there was a ring around the sun about 70,000 

 miles in height. (Of course these are not his exact words ; 

 what he actually stated was that the ring was about a digit 

 in breadth.) This is the exact height assigned to the 

 coronal ring by the observers of the eclipse of last year. 

 The ring seemed to be of a reddish colour. Another 

 clergyman, Vallerius, states also that the ring was of this 

 colour, but adds that at a considerable distance from the 

 sun it had a greenish hue. This suggests the idea that the 

 outer corona was seen also by Vallerius, and that it had 

 considerable breadth. The reddish colour of the inner 

 light portion would correspond to the colour it would have 

 if it consisted in the main of glowing hydrogen. If that 



