54S 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



corona of 1842 resembled, if it did not surpass, 

 that of last July. 



" I had imagined," says Baily, "that the co- 

 rona, as to its brilliant or luminous appearance, 

 would not be greater than that faint crepuscular 

 light which sometimes takes place (sic) in a sum- 

 mer evening, and that it would encircle the moon 

 like a ring. I was, therefore, somewhat surprised 

 and astonished at the splendid scene which now 

 so suddenly burst upon my view." 



The light of the corona was so bright, 0. Struve 

 states, that the naked eye could scarcely endure 

 it; "many could not believe, indeed, that the 

 eclipse was total, so strongly did the corona's 

 light resemble direct sunlight." Thus, while as 

 regards extent the corona in 1842 presented the 

 appearance to be expected at the time of maxi- 

 mum solar disturbance if our theory is sound, its 

 brightness was that corresponding to a time of 

 minimum disturbance. Its structure corresponded 

 with the former condition. The light of the co- 

 rona was not uniform, nor merely marked by 

 radiations, but in several places interlacing lines 

 of light could be seen, Arago, at Perpignan, ob- 

 served with the unaided eye a region of the co- 

 rona where the structure was as of intertwined 

 jets, giving an appearance resembling a hank of 

 thread in disorder. 



Certainly, for an eclipse occurring two years 

 from the time of minimum and five years from 

 the time of maximum disturbance, that of July, 

 1842, 1 has not supplied evidence favoring the 

 theory with which we started. Whether any 

 other theory of association between the co- 

 rona and the sun-spots will better accord with 

 the evidence hitherto collected remains to be 

 seen. 



Turn we now to the eclipse of 1851, occurring 

 nearly midway between the epochs of maximum 

 solar disturbance (1848) and minimum solar dis- 

 turbance (1856). I take the account given by 



1 The actual condition of the sun in 1842 may be in- 

 ferred from the following table, showing the number 

 of spots observed in 1837, the preceding year of maxi- 

 mum disturbance, in 1842, and in 1841, the following 

 year of minimum disturbauce. The observer was 

 Schwabe, of Dessau : 



Only it should be noticed that nearly all the spots seen 

 in the year 1844 belonged to the next period, the time 

 of actual minimum .occurring early in 1844. 



Airy, our Government astronomer, as he was one 

 of the observers of the eclipse of 1842 : 



" The corona was far broader," he says, " than 

 that which I saw in 1842. Eoughly speaking, the 

 breadth was little less than the moon's diameter, 

 but its outline was very irregular. I did not no- 

 tice any beams projecting from it which deserve 

 notice as much more conspicuous than the others ; 

 but the whole was beamy, radiated in structure, 

 and terminated — though very indefinitely — in a 

 way which reminded me of the ornament fre- 

 quently placed round a mariner's compass. Its 

 color was white, or resembling that of Venus. I 

 saw no flickering or unsteadiness of light. It was 

 not separated from the moon by any interval, nor 

 had it any annular structure. It looked like a ra- 

 diated luminous cloud behind the moon." 



The corona thus described belongs to that 

 which our theory associates with the period of 

 maximum rather than of minimum solar disturb- 

 ance. Definite peculiarities of structure seem to 

 have been more numerous and better marked 

 than in 1842. It accords with our theory that 

 1851 was a year of greater solar disturbance than 

 existed in 1842, as the following numbers show: 



YEAR. 



1842. 

 1851. 

 1860. 



Days of 

 Observation. 



307 

 308 

 332 



Days without 

 Spots. 



64 



New Groups 

 observed. 



68 

 141 

 211 



I have included the year 1860, as we now,pro r 

 ceed to consider the corona then seen by Airy. 

 The year 1860 did not differ very markedly, it 

 will be observed, from 1851, as regards the num- 

 ber of new groups of spots observed by Schwabe, 

 especially when account is taken of the number 

 of days on 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 considerable body, but I did not re- 

 mark either by eye-view or by telescope-view any- 



1 The following table shows the position occupied 

 by the years 1851 and 1860 in this respect, as compared 

 with the year 1848 (maximum next preceding 1851), 

 1856 (minimum next following 1851), and 1867 (mini- 

 mum next following 1860) : 



TEAR. 



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. 



