4 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of these eruptions is seen on the eastern edge of the sun, a 

 spot is sure to appear on the day following. This connection 

 has been so uniform that for several months he has been able 

 to predict the appearance of a spot by simple examination of 

 tlie spectrum of the eruption. Afterward, by examining his 

 older observations, he has found a hundred similar verifica- 

 tions. In fact, it is hardly necessary to examine the spectrum 

 of the eruption, its peculiar physical character being nearly 

 as good. In the fiist jilace, the light of the jets exhibits a 

 great brilliancy. The hydrogen ray C assumes a very deep 

 and singular tint. The flames are very dense, terminating in 

 sharp and often straight points; when bent back, they are 

 very unstable, changing from one instant to another. The 

 height of the jet is generally but not always considerable ; 

 sometimes the jets are low, but very sharply terminated. 



From a comparison of these spectra with those of the spots, 

 Secchi concludes that the spectrum of the metallic protuber- 

 ances is the same with that of the spot, which on the edge of 

 the sun appears by its direct rays, while on the disk the rays 

 are reversed. The spots are produced by masses of metallic 

 vapor bursting out from the interior of the sun. These va- 

 pors need not rise to a great elevation ; it is suflicient if they 

 rise above the general level of the photosphere. They then 

 rest suspended and floating in the photosphere itself like 

 islands, but being sunk to its level they look like cavities. 

 These masses are of course coated, and therefore absorb the 

 rays of light and heat, but the surrounding photosjDheric 

 mass gradually encroaches upon and dissolves them. 



Secchi finally remarks that there are still some details to 

 be explained which will require time to work up. He difiers 

 completely from Faye, who attributes the spots to revolving 

 storms or solar cyclones, stating that there are not more than 

 five or six cases of spots showing a motion of revolution in 

 the course of a year. 



SECCHI ON SOLAR PROTUBERANCES. 



The observations of solar protuberances by Secchi for the 

 latter half of 1872 have been published, and form a very 

 valuable contribution to what he styles " solar meteorology." 

 The conclusions to which he has been led are thus epitomized: 



1. The protuberances from August 13 to December 31, 



