1869.] 



Observations of the Sim. 



507 



ther and more successful observations. Should you think fit to publish 

 them, I hope you will do so, as I cannot command the necessary leisure to. 

 follow them up myself to their legitimate conclusion. 



On the 3rd instant I learnt (as I informed you) that the spectrum of 

 tbe solar envelope was visible with the spectroscope at my command, appa- 

 rently without difficulty. On the following day I saw the same pheno- 

 mena, and was enabled to form a fair mental picture of the distribution of 

 the luminous regions surrounding the sun. Two very fine prominences 

 were particularly examined, one of which was evidently a large cloud float- 

 ing 1' to 2' above the surface. 



On the 5th, while traversing over a new prominence to learn its shape 

 and dimensions, I became aware of a fourth line in the neighbourhood of Gk 

 Its position was determined without difficulty with reference to the rest of 

 that crowded group of solar lines. It was identical with the thick line at 

 2796 of Kirchhoff's chart. I have seen the same line repeatedly since, and 

 have satisfied myself of the identity stated. 



It rained pretty heavily on the night of the 5th ; and the next morning 

 I was disappointed by seeing no remarkable prominences, and but faint in- 

 dications, in many parts, of the solar envelope. In the afternoon, however, 

 the air, I suppose, being clearer, I could again see the luminous spectrum 

 in nearly every part. But there were very few elevated masses. Having 

 traversed round the whole circumference, I returned, after perhaps an hour's 

 search, to examine again a moderately striking elevation which I had no- 

 ticed at setting out ; and for this purpose I directed the slit as a tangent 

 to the surface at the place — the most favourable position for getting a good 

 view of the lines. 



Immediately I remarked that the red line was very brilliant, and glan- 

 cing up the spectrum saw that the orange and blue lines were also much 

 more intense than usual. My eye was next caught by a fainter red flash, 

 which I soon succeeded in seeing more steadily. Concluding that it was 

 the line which Mr. Lockyer had seen ' f occasionally," I only staid to es- 

 timate its position, and proceeded to bring the violet end into the field to 

 have another look at the line in that region and to see F to better advan- 

 tage. In so doing I noticed another line (the sixth) between F and G. 



Before going any further I must take the liberty of christening these 

 lines for reference. Leaving a and /3 for C and F if wanted, I would call 

 the orange line near D the violet one y, the red line near C e, and the 

 last mentioned £. The solar bright-line series is then as follows : — 



a = C 

 /3 = F- 



Kirchhoff's 694 

 2080 



d near D 

 y near G 

 e near C 



1014 very nearly. 



£ between F and G . . . . 



2/96 

 655 about. 

 2596 nearly. 



