18 The Total Eclipse of the Sun, April 16, 1893. 



short exposures, so that the phenomena can be recorded at short 

 intervals during the eclipse. 



(2) The most intense images of the prominences are produced bj 

 the H and K radiations of calcium. Those depicted by the rays of 

 hydrogen and helium are less intense, and do not reach to so great a 

 height. 



(3) The forms of the prominences photographed in monochromatic 

 light (H and K), during the eclipse of 1893, do not differ sensibly 

 from those photographed at the same time with the coronagraph. 



(4) The undoubted spectrum of the corona in 1893 consisted of 

 eight rings, including that due to 1474 K. The evidence that these 

 belong to the corona is absolutely conclusive. It is probable that 

 they are only represented by feeble lines in the Fraunhofer spectrum r 

 if present at all. 



(5) All the coronal rings recorded were most intense in the 

 brightest coronal regions, near the sun's equator, as depicted by the 

 coronagraph. 



(6) The strongest coronal line, 1474 K, is not represented in the 

 spectrum of the chromosphere and prominences, while H and K do 

 not appear in the spectrum of the corona, although they are the most 

 intense radiations in the prominences. 



(7) A comparison of the results with those obtained in previous 

 eclipses confirms the idea that 1474 K is brighter at the maximum 

 than at the minimum sun-spot period. 



(8) Hydrogen rings were not photographed in the coronal spec- 

 trum of 1893. 



(9) D 3 was absent from the coronal spectrum of 1893, and reasons 

 are given which suggest that its recorded appearance in 1882 was 

 simply a photographic effect due to the unequal sensitiveness of the 

 isochromatic plate employed. 



(10) There is distinct evidence of periodic changes of the con- 

 tinuous spectrum of the corona. 



(11) Many lines hitherto unrecorded in the chromosphere and 

 prominences were photographed by the prismatic cameras. 



(12) The preliminary investigation of the chemical origins of the 

 chromosphere and prominence lines enables us to state generally that 

 the chief lines are due to calcium, hydrogen, helium, strontium, iron, 

 magnesium, manganese, barium, chromium, and aluminium. None 

 of the lines appear to be due to nickel, cobalt, cadmium, tin, zinc, 

 silicon, or carbon. 



(13) The spectra of the chromosphere and prominences become 

 more complex as the photosphere is approached. 



(14) In passing from the chromosphere to the prominences, some 

 lines become relatively brighter but others dimmer. The same line 

 sometimes behaves differently in this respect in different prominences. 



