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playing in the sun's atmosphere. The summit of a prominence 

 quiet at its base will at times be torn to pieces by such winds. 

 The dhection of these currents as indicated by the inclinations of 

 the summits of the flames formed the subject of long continued 

 study by Secchi. As a result of his researches he arrived at the 

 conclusion that there is a well marked current flowing from the 

 equator to the poles, with which conclusion Young is inclined to 

 agree. Yet as more observations seem to be needed to solidly 

 establish this important point, it is one of those which receives 

 especial attention in the observations of chromosphere and 

 prominences made at Stonyhurst. There are other motions of 

 these suspended cloud masses which are interesting. For 

 instance, on April 3, 1872, Secchi observed a cloud which moved 

 so rapidly upwards from the limb that between 8^ 44™ and 9** 10"" 

 the distance of the summit from the sun's surface had increased 

 from 4' 19" to 7' 29". The increase in height of the prominence 

 was therefore at the rate of 85,500 miles in 26 minutes, or about 

 55 miles a second. 



But by far the most interesting of all solar displays are the 

 eruptive prominences. Not so extensive as the quiet prominences, 

 they are as a rule much more brilliant. They differ too in this, 

 that their lives are generally very short. Tlieir spectrum at 

 times is a very complicated one, and although the chief materials 

 out of which they are formed are hydrogen and helium, yet 

 their spectrum is rich in such metals as iron, sodium, magnesium, 

 calcium, and titanium. But they are most remarkable on 

 account of their rapid changes of form, and the velocities with 

 which they are projected upwards. On October 16, 1871, Secchi 

 observed and drew a remarkable outburst in the presence of 0. 

 Struve, the Director of the great Eussian Observatory of Pulkowa, 

 At 9-10 when the sun was first observed, nothing remarkable on 

 this limb had been noticed ; but at 9-30 a conical shaped flame 

 was detected at about 85° from the N. point towards the W., 

 and about 5° from the flame a large diffused mass of cloud. At 

 9-36 the flame had increased both in length and breadth, having 

 absorbed the cloud. At 9-43 it assumed a fan shape with 

 brilliant jets, the height being now about 64", i.e., nearly 29,000 

 miles. The storm culminated at 9-49. The height of some 

 isolated fragments was now about 240", about four times what it 

 had been six minutes previously, and the breadth 236", with a 

 rate of ascent of 217 miles a second. An injection of heavy 

 metals at the base of the flame was also detected by the spec- 

 troscope, among them being iron, sodium, and magnesium. 

 Three principal jets could be distinguished, the highest attaining 

 its maximum of 176", or about ten times the earth's diameter, 

 at 9'56. By 10-12 the whole storm had passed away, and there 

 remained but two small jets to mark the seat of this mighty 



