62 HERSCHEL AND HIS WORK 



not broad the twelfth part of the diameter of tin moon. 

 plan. -i did appear very black, and her disk v. ry 

 well defined, within tin- wbiten- s \\hichencompassed 

 it about, and whose colour was the same \vith that of 

 a white crown or luilo, of about four or five de- 

 in diam. I.T. which accompanied it, and had the moon 

 for its centre. ... A little time after the sun had 

 began to appear again, the whiteness and th crown; 

 which did encompass the moon, did entirely vani 

 Duillier's comment on this description of the corona is : 

 " The moon's atmosphere cannot well be supposed less 

 than of 130 miles, in perpendicular hi- lit. . . . Though 

 it was very plain that the atmosphere of the moon 

 must needs show itself, in the time of a total eclipse 

 of the sun; yet I do not know that anybody did 

 think of this, till in the last month of May, many 

 persons did actually see it." * 



At Zurich Dr. Scheuchzer, in four lines of Latin, 

 describes how they had a solar eclipse, at once total 

 and annular; total, because the sun was wholly 

 covered by the moon ; annular, not properly so called, 

 but by refraction, since around the moon appeared a 

 ruddy brightness (f vigor rutttans), caused by rays 

 refracted through the moon's atmosphere. 



The blood-red streak, the corona, the ruddy bright- 

 ness observed during the total eclipse of 1706, the 



1 A letter from a friend at Marseilles informed Duillicr that, during 

 totality, "there did remain one bright digit, all about the globe of the 

 moon" (Phil. Trans. (No. 306), p. 2237). 



* "The red prominences were first seen daring the solar eclipse of 

 8th July 1842 " (Proctor, Encyc. Brit. vol. ii. p. 788). Baily was not 

 the first to see them. Captain Stannyan and Dr. Scheuchzer carried off 

 the honour 136 years earlier. Facio Duillicr has the credit of first 

 describing the corona. 



