No, 1.] ARMSTRONG — LAST SOLAR ECLIPSE. 17 



field of view. This telescope, although its aperture was 14 

 iuches, had a ibcal length of only 54 inches; a proportion calculated 

 to produce images fourteen times as bright as in an ordinary 

 instrument. His point of observation, Sholoor, in the Neilgherry 

 Hills, also was at an unusual altitude. 



What each of tliese physicists was successful in seeing may 

 be best gathered from their ow^u descriptions. 



Ilespighi says, in speaking of the coloured zones visible in his 

 instrument when examining the Corona and Halo, that there waS 

 " one in the red corresponding with the line C (Hydrogen) ; an- 

 " other in the green, probably coinciding with the line 1474 of 

 " Kirchoff's scale (the unhnown mutter), and the third in the blue, 

 " perhaps coinciding with F (Hydrogen). The green zone was 

 '' the brightest, the most uniform and the best defined. The red 

 " zone was also very distinct and well defined, while the blue 

 " zone was faint and indistinct. The li'reen zone was well 

 '■ defined at the summit, thouuh less bright than at the base, 

 *' its form was sensibly circular and its height about G' or 7'. 

 " The red zone exhibited the same form, and approximately 

 " the same heiuht as the i^Teen, but its lioht was weaker and 

 ^' less uniform." He then goes on to say, "these coloured zones 

 '• shone out upon a faintly illuminated ground without any 

 " marked trace of colour. If the Corona or Halo contained rays 

 " of any other colour, their intensity must have been so feeble 

 " that they were merged in the general illumination of the 

 " field." 



M. Janssen states his experience thus: " The reasons/' he 

 says, "which militate in favour of an objective solar origin (i.e., 

 " of the coronal phenomena) acquire an invincible force when we 

 " examine the luminous elements of the phenomena. In fact 

 " the spectrum of the Corona (and Halo) has not shewn itself 

 " (in my telescope) continuous, as it has hitherto been formed, 

 " (i.e., by those observers, who differed from Professor Young 

 " in 1870), but remarkably complex. I have discovered in it 

 " the bright lines, though much enfeebled, of hydrogen gas, 

 " which forms the principal element of tlie prominences and 

 " sierra ; the bright green line which has already been noted 

 " during the eclipses of 18G9 and 1870, as well as some other 

 " fainter lines ; and the dark lines of the ordinary solar spec- 

 " trum, notably that of sodium. These dark lines are much 

 " more difiicult to perceive. These facts prove the existence of 

 Vol. VII. B No. 1. 



