1915] on the Total Solar Eclipse of 1914 363 



coronal spectrum on the photograph is undoubtedly that of a series 

 of bands or flutings. From a study of the position of the slit relatively 

 to the corona, it appears that the spectrum is not that of the upper 

 chromosphere, nor that of the lower corona, but of the roots of the 

 streamers on the E. side of the sun. The spectrum is unique, and 

 suggests, as many another physical experiment, a fresh problem for 

 further investigation. 



We have dwelt upon our own results and operations, as these are 

 naturally more familiar to us than those of the other British expedi- 

 tions. Unfortunately two of the other three expeditions were entirely 

 spoilt by adverse circimi stances. It was a hard fate which compelled 

 Professor Fowler to be stranded at Riga, and to be unable to proceed 

 to his destination on account of the war. It was perhaps a harder 

 fate which, frustrating all the careful preparations and adjustments 

 of instruments at a chosen site at Theodosia in the Crimea, befell 

 Professor Newall. For he had the mortification of being robbed of a 

 view of the eclipsed sun by purely local clouds. Two miles from his 

 station the Italian expedition under Professor Ricco enjoyed a cloud- 

 less sky. We sympathize with these astronomers in their naturally 

 keen disappointment. At the same time we can rejoice in the success 

 of the Greenwich observers, Mr. Jones and Mr. Davidson, at Minsk. 

 With the Thompson coronagraph they obtained seven large scale 

 photographs of the corona full of fine detail. More interesting still 

 was the employment of two photographic cameras, with green colour 

 screens, to obtain information as to the presence and distribution of 

 coronium. In front of the object-glass of each of these a prism was 

 placed. Its function was to disperse the continuous light passing 

 through the monochromatic filters. Had coronium been present it 

 would have shown itself as a bright ring or portions of a ring round 

 the eclipsed sun. The resulting photographs show that it was entirely 

 absent. This observation, which corroborates and strengthens the 

 value of those made by other observers in this eclipse, is of great 

 importance. The corona was bright, and yet there was no green 

 coronium radiation as we should have naturally expected. As we 

 have already noted, the faintest possible trace of this radiation appears 

 in a band or fluting on our own photograph of the coronal spectrum. 



The Greenwich observers have also been successful in another 

 direction. With the Hills quartz spectroscope, specially improved 

 for this occasion in various adjuncts, the spectrum of the " flash " has 

 been photographed down to wave-length 3118 in the ultra-violet. 

 This is considerably farther than had been photographed before, as 

 far as accurate measures of the wave-lengths of the lines are concerned. 

 At least 120 lines of a shorter wave-length than those which were 

 photographed by Mitchell in 1905 have been measured. 



The extended spectrum of the flash in the ultra-violet secured 

 by the Greenwich observers, and the novel and unique spectrum of 

 the corona in the red photographed by the Stonyhurst observers, are 



