1888.] 



Total Solar Eclipse of August 29, 188b*. 



429 



able conditions under which the observations were made. The second 

 part gives the results of the observations. These were of two kinds. 



1. Before and after totality the order of appearance and disappear- 

 ance of a number of bright lines in the spectrum of the chromosphere 

 ami inner corona was watched. The lines selected were those observed 

 by Mr. Lockyer in the Egyptian eclipse of 1882, and the observations 

 were undertaken with a view to the confirmation of his results. 



The lines are denoted for convenience by small letters as follows : — 



a 4870-4 



I 4871 2 



c 4890-0 



d 4890-4 



A 



4917-9 

 4919-6 

 4923-1 



x 



h 4932-5 



i 4933-4 



k 4956-5 



I 4970-0 



With this nomenclature a table given by Mr. Lockyer in a short 

 account of his results (' Roy. Soc. Proc.,' vol. 34, 1863, pp. 291, &c.) 

 shows that lines g and I are seen by Tacchini in prominences, while 

 a, by c, d, e, /, and k are seen in spots. 



Mr. Lockyer saw g and % 7 minutes before totality, 

 and in addition A: and IS „ „ 

 and all the lines . . 2 „ ,, 



In my own observations I saw g 3 minutes before totality, 

 and in addition i 40 seconds ,, 



while the moment of appearance of all the lines was indistinguishable 

 from the commencement of totality. 



After totality clouds obscured the sun for a short time ; but on 

 their clearing the visibility of g and k was noted ; i could not be seen. 



The three lines g, i, and k were extremely short, and did not appear 

 to extend beyond the chromosphere before and after totality. 



The unfavourable conditions under which the observations were 

 made as compared with Mr. Lockyer's — with a low sun and through 

 passing clouds, and an atmosphere charged with moisture which 

 doubtless diminished the light in this region of the spectrum con- 

 siderably — perhaps account in some measure for the striking differ- 

 ence in vividness of the phenomena. The solar activity was also 

 much nearer minimum in 1886 than in 1882. As far as they go, how- 

 ever, the observations are confirmatory of Mr. Lockyer's, except in 

 the visibility of the line k after totality. This line was not noted 

 before totality, and it is possible that the observation may be spurious, 

 although the evidence for it is as good as that for all the obser- 

 vations, which were found to be generally of a difficult character. The 

 instrument used was a 6-inch refractor by Simms, with a grating 

 spectroscope, the grating being 1~ inch square, ruled with 17,0(J0 lines 

 to the inch. The second order of spectrum was used. 



