CAMPBELL— CROCKER ECLIPSE EXPEDITION. 249 



edly strengthened a little by the superposition of these bands of 

 continuous light with the green ring. The origin of the continuous 

 bands has been under discussion. It has seemed to me that the ma- 

 terials responsible for the green ring yield continuous radiations 

 more abundantly than special radiations, for it must be remembered 

 that the latter are condensed in the slender ring, whereas the faint 

 continuous bands stretch from end to end of the spectrum. The 

 energy represented by the green ring, and in fact by all the bright 

 coronal rings, is exceedingly slight in comparison with the sum total 

 of coronal radiations, and apparently represents but a small fraction 

 of the radiations proceeding from the bright ring materials them- 

 selves. It has been suggested that the faint bands passing through 

 the condensations in the green ring may proceed principally from 

 prominences ; and, again, that they may have had their origin in 

 photospheric light passing through depressions in the moon's edge, 

 owing to the exposures having begun too soon after contact II., or 

 continued too close to contact III. I do not think the point has 

 been well taken, for the relationship of the continuous bands to the 

 green condensations is plainly evident, and there is no apparent rea- 

 son why these condensations should be related to depressions in the 

 moon's edge. Again, there is a considerable number of extant coro- 

 nal spectrograms bearing upon the subject. SHde No. i8 is from 

 Lockyer's photograph of 1905. The green coronal ring to the right 

 contains a prominent condensation through which passes a strong 

 band of continuous radiation. This band is shown on the left in 

 the H and K calcium region of the same spectrogram. The band 

 misses the calcium prominences very skilfully. In the same way 

 the hydrogen images of the prominences on the same spectrogram 

 do not show the continuous band as passing through them. 



The coronal spectrograms of recent decades are essentially 

 agreed that the continuous radiations of the bright inner corona are 

 but feebly and inappreciably afit'ected by Fraunhof er absorption, thus 

 establishing, in my opinion, that the inner coronal materials are 

 chiefly incandescent and supply us with radiations of their own, to 

 which reflected or diffused photospheric light makes but a small 

 addition. The spectrum of the outer corona, on the contrary, say 

 regions lying ten or fifteen minutes, or farther, from the sun's edge, 



