|g The Outline of Science 



extends from .5.000 to 10,000 miles in thickness a "sea" of red 

 tumultuous surging fire. Chief among the glowing gases is the 

 vapour of hydrogen. The intense white heat of the photosphere 

 beneath shines through this layer, overpowering its brilliant red- 

 1'rom the uppermost portion of the chromosphere great 



tongues of glowing hydrogen and calcium vapour shoot out 

 for many thousands of miles, driven outward by some prodigious 

 expulsive force. It is these red "prominences" which are such 

 a notable feature in the picture of the eclipse of the sun already 

 referred to. 



During the solar eclipse of 1919 one of these red flames rose 

 in less than seven hours from a height of 130,000 miles to more 

 than 500,000 miles above the sun's surface. This immense column 

 of red-hot gas, four or five times the thickness of the earth, was 

 scaring upward at the rate of 60,000 miles an hour. 



These flaming jets or prominences shooting out from the 

 chromosphere are not to be seen every day by the naked eye; 

 the dazzling light of the sun obscures them, gigantic as they are. 

 They ean be observed, however, by the spectroscope any day, and 

 they are visible to us for a very short time during an eclipse of the 

 sun. Some extraordinary outbursts have been witnessed. Thus 

 the late Professor Young described one on September 7, 1871, 

 when he had been examining a prominence by the spectroscope: 



It had remained unchanged since noon of the previous 

 day a long, low, quiet-looking cloud, not very dense, or 

 brilliant, or in any way remarkable except for its size. At 

 l _':.{<) p.m. the Professor left the spectroscope for a short 

 time, and on returning half an hour later to his observations, 

 he was astonished to find the gigantic Sun flame shattered to 

 pieces. The solar atmosphere was filled with flying debris, 

 and some of these portions reached a height of 100,000 miles 

 above the solar surface. Moving with a velocity which, even 

 at the distance of 93,000,000 miles, was almost perceptible 

 to the eye, these fragments doubled their height in ten 

 minutes. On January 30, 1885, another distinguished solar 



