THE SOLAR ECLIPSE OF 1871. 147 



This is easily answered. These blazing gases must, as we 

 proceed from the surface of the sun downward, become so 

 condensed by the pressure of their own superincumbent strata, 

 as to produce a continuous spectrum of great brilliancy. With 

 such a background the bright stripes would be confounded and 

 lost to sight. Besides this, the outer film of cooler vapor 

 through which our vision must necessarily penetrate before 

 reaching the luminous solar surface, will produce the dark lines 

 exactly where the bright stripes should be, and thus effectually 

 obliterate them ; or, in other words, the intervening non-lumi- 

 nous vapors are opaque to the particular rays of light which the 

 bright vapors of the same substance emits. 



Therefore, according to this theory, if we could sweep away 

 these outside darkening vapors, and screen off the inner layers 

 of denser blazing matter which produces the continuous back- 

 ground, we should have a spectrum displaying a multitude of 

 bright stripes exactly where the black lines of the ordinary 

 solar spectrum appear. 



Secchi announced that these bright lines were to be seen 

 under favorable circumstances, when, by skilful management, 

 the rays from the edge of the sun were so caught by the slit of 

 the spectroscope as to exhibit only the spectrum of the super- 

 ficial layer of the sun's bright surface. This was disputed at 

 the time by Mr. Lockyer, who, I suspect, omitted to consider 

 the atmospheric difficulties under which English astronomers 

 work, and the fact that the atmosphere of Italy is exceptionally 

 favorable for delicate astronomical observation. 



If he had fairly considered this I think he would agree with 

 me in concluding that an observation of this kind, avowedly 

 made with great difficulty and questionable distinctness by so 

 skilful a spectroscopic observer as Father Secchi, could not pos- 

 sibly be seen by any human eyes through a London atmosphere. 



Subsequently Professor Young startled the astronomical 

 world by the announcement that, at the moment when the 

 thinnest perceptible thread of the sun' s edge was alone display- 

 ed during the eclipse which he observed, the whole of the dark 

 lines of the .solar spectrum flashed out as bright stripes in a 

 most unmistakable manner. This observation is now fully 

 confirmed. The first telegrams from Mr. Pogson, the Govern- 

 ment astronomer of Madras, and from Colonel Tennant, both 

 announce this most positively, Colonel Tennant's words being, 

 " the reversion of the lines fully confirmed. " A similar result 

 was obtained by some, but not by all, of the Ceylon observers. 



