No. 1.] ARMSTRONG— LAST SOLAR ECLIPSE. 15 



The principal questions then, pending at the time of the Eclipse 

 of 1871, AYcre somewhat as follows : — What order of Spectra do 

 the Corona and Halo give ? Are they of the same or of diverse 

 orders, or are they blended ? At what distance from the Sun's 

 limb can a spectrum be obtained and where is the bounding line, 

 if any, between the Corona proper and the Halo ? Is the light 

 of either or both polarised and, if ^o, how ? And finally, what 

 spectroscopic indications are there of the presence of an, as yet, 

 terrestrlallij unhiown form of matter in these wonderful solar 

 appendages, if they be such ? 



To all these enquiries it is satisfactory to state that answers 

 were forthcoming, and of such a kind as to put an end to specu- 

 lation as to the coronal nature. 



In order to make what is to follow clear, it may be proper here 

 to mention that Angstrom in the year 1867, when ?pectroscopi- 

 cally examining the Aurora Borealis and Zodiacal light, found 

 in both spectra a hrigltt green line, of wave length = 5567, sup- 

 posedto correspond with ^ faint line numbered 1474 on Kirchoff's 

 scale, and grouped by him among the four or five hundred lines 

 of Iron ; but not as one of those that are charaef eristic of that 

 metal. On one occasion when the sky was peculiarly phosphor- 

 escent, Angstrom detected this same line, not only in the Zodi- 

 acal light, but in all parts of the heavens ; and on each occasion 

 it was present unassocidted with any other lines of iron ; a fact 

 that may be construed as indicating the presence of some new 

 form of matter, hitherto unknown, inasmuch as the only appear- 

 ance of this particular line with which we are terrestrially ac- 

 quainted is as a supposed hut insignificant member of the iron 

 group. During the Eclipses of both 1869 and 1870, Professor 

 Youno: announced that he had detected this same line in the Co- 

 rona and Halo, and in a bright and characteristic form. And 

 the matter to which this line is supposed to be due afterwards 

 received the name of " 1474- matter.*' 



The import of this discovery, supposing it to be valid, cannot 

 fail to be patent to the reader, for it reveals the existence of a 

 new and mysterious form of matter, of which we had no previous 

 conception, present alike in the Aurora, Zodiacal-light, Coronal 

 appendages and even in the interstellar regions themselves ; we 

 may say indeed everywhere and all-pervading. What, we at once 

 ask, is its nature and what its function in the economy of nature ? 

 But these are questions to which, as yet, we have no satisfactory 

 reply. 



