384 .S"/'?/- K'-iif* '.-/ .1% 28, 1900. 



is * inches long, ami r\tcn<ls from X 350 to X 510. The width corre- 

 sponding to the sun's diameter is 0*6* inch. 



The finer flash spectrum lines in many of the photographs are par- 

 ticularly well defined in the ultra-violet. 



The first four photographs of the series' are much over-exposed ami 

 fogged, and only the stronger chromosphere arcs are visible at the 

 edge of the continuous spectrum. In the succeeding images, the sky 

 illumination becoming much diminished, the bright lines show up 

 clearly on a light background. 



In No. 9 the Hash spectrum is fully developed in a rift in the con- 

 tinuous spectrum. This rift extends from position angle 140 to 148 J , 

 and includes a region between 67" and 75 south latitude. The 

 bright lines crossing the rift are beautifully defined throughout the 

 spectrum, and in the ultra violet they can be traced nearly as far as 

 the continuous spectrum. The Fraunhofer lines are well defined upon 

 the continuous spectrum, where the latter has not been over-exposed, 

 and the whole spectrum in the ultra-violet is a mixture of bright and 

 dark lines. 



Accurate determinations of wave-length will result from the measure- 

 ment of this negative. 



No. 11. This was exposed for 10 seconds at the greatest phase of 

 the eclipse. The continuous spectrum is broken up into five narrow 

 bands, and the flash spectrum lines form long arcs crossing the bands. 

 Most of these arcs extend over nearly 80 of the limb, and cover the 

 entire south polar region, from latitude - 75 on the east side to 

 latitude - 28 on the west. 



The bright lines on this negative are more strongly impressed than 

 on any of the others, and they can be clearly traced up to the end of 

 the continuous spectrum at X 350. The dark lines of the Fraunhofer 

 spectrum are still traceable on .the narrow strips of continuous spec- 

 tmm. 



This negative will give good wave-length determinations for all the 

 finer lines l>etween X 350 and X510. 



Good images of the flash spectrum are also impressed on photographs 

 Nos. 10, 12, and 13. 



(1) In its main features the flash spectrum at the south pole of the 

 sun is the same as in low latitudes. 



(2) No essential change is shown after an interval of four years ; 

 the spectra photographed by Shackleton, in 1896, and those obtained 

 in 1898 and 1900, all appear to be identical so far as it has been 

 possible to compare them. 



(3) The flash spectrum, therefore, is probably as constant a feature 

 of the solar surface as is the Fraunhofer spectrum. 



