16 ROUGH WAYS MADE SMOOTH. 



differ very markedly, it will be observed, from 1851, as 

 regards the number of new groups of spots observed by 

 Schwnbe, especially when account is taken of the number 

 of days in which the sun was observed in these two years, 

 But 1860 was a year of maximum solar disturbance, whereas 

 1851 was not 1 



Airy remarks of the corona in 1860 : ' It gave a con- 

 siderable body, but I did not remark either by eye-view or 

 by telescope-view anything annular in its structure ; it 

 appeared to me to resemble, with some irregularities (as I 

 stated in 1851), the ornament round a compass-card.' 



Bruhns of Leipsic noted that ^e corona shone with an 

 intense white light, so lustrous as to dim the protuberances. 

 He noticed that a ray shot out to a distance of about 

 one degree indicating a distance of at least 1,500,000 miles 

 from the sun's surface. This was unquestionably a coronal 

 appendage as neither the direction nor the length of the ray 

 varied for ten seconds, during which Bruhns directed his 

 attention to it. Its light was considerably feebler than that 

 of the corona, which was of a glowing white, and seemed to 

 coruscate or twinkle. Bruhns assigned to the inner corona 

 a height varying from about 40,000 to about 80,000 miles. 

 But this was unquestionably far short of the true height. In 

 fact, Secchi's photographs show the corona extending to a 

 distance of at least 175,000 miles from the surface of the 



1 The following table shows the position occupied by the years 1851 

 and 1860 in this report, as compared with the year 1848 (maximum 

 next preceding 1851), 1856 (minimum next following 1851) and 1867, 

 minimum next following 1860 : 



1848 

 1851 

 1856 

 1860 

 1867 



A comparison of the three tables given in these notes and the text will 

 afford some idea of the irregularities existing in the various waves of 

 sun-spots. 



