154 On the Total Solar Eclipse of May 17, 1882. [Apr. 19, 



A strong prominence, which was cnt by the slit, gives a com- 

 plicated spectrnm. The calcium lines, and especially the lines H and 

 K, stand out prominently. Then, as might be expected, all the 

 hydrogen lines are represented, including those in the ultra-violet, 

 photographed by Dr. Huggins in star spectra. Some unknown lines 

 bring up the total number of lines photographed to 29. In the 

 outer regions of the corona the continuous spectrum is traversed by 

 the reversal of the solar line G and by a number of faint lines. 

 About thirty of these coronal lines have been measured. 



In conclusion, we may briefly review the results we have obtained. 

 The direct photographs of the corona are chiefly of interest in con- 

 nexion with previous and future eclipses, and we believe that those 

 we have obtained will be found of value, as they have been taken 

 during a, time of maximum sun-spots, as they extend further than any 

 photographs previously obtained, and as the position of the corona in 

 the sky has been fixed by means of them to within a fraction of a 

 degree. 



The photograph taken with the prismatic camera is of importance 

 when we come to compare spectra of different prominences, which are 

 found to give lines with different relative intensities caused no doubt 

 by differences of temperature. Two prominence lines in the ultra-red 

 have been discovered. It is also proved that the green line of the 

 corona is a line specially belonging to the corona. It is only very 

 faintly present in the prominences, but forms a distinct ring round a 

 large part of the solar disk. A faint ring corresponding to D 3 is also 

 seen. 



The photograph of the spectrum of the corona and prominences has 

 yielded an abundant harvest. Twenty-nine lines of one prominence 

 have been photographed, and the great importance which the metal 

 calcium plays in the solar eruptions has been emphasized. Other 

 lines well known hitherto as chromospheric lines, but not traced in 

 the prominences, are now shown to belong to them also, and a number 

 of unknown lines, especially in the ultra-violet, has been added to the 

 list. 



As regards the corona we may point out that only one line has 

 hitherto been well determined, and accepted as a true corona line, 

 though one or two more have been suspected. During the la.te eclipse 

 the corona seems to have been especially rich in lines. Thollon 

 observed some in the violet without being able to fix their position; 

 and Tacchini could determine the position of four true corona lines 

 in the red. We have been able to photograph and measure about 

 thirty additional lines. 



The fact that part of the outer corona shines by reflected light has 

 been once more proved by the presence of the dark Fraunhofer set of 

 lines G, and if any doubt previously existed respecting the presence 



