406 Dynamic Theory. 



No. of Lines. No. of Lines. 



Hydrogen 4 Manganese 57 



Sodium /9 Chromium 18 



Barium 11 Cobalt 19 



Calcium 75 Nickel 33 



Magnesium 7 Zinc 2 



Aluminum 2 Copper 7 



Iron 450 Titanium , 118 



In addition to these, Lockyer gives cadmium as detected in the solar 

 spectrum, and Prof. C. A. Young, of Dartmouth College, claims also irid- 

 ium, sulphur, cerium and strontium. Thus we have 19 at least of our 

 elements represented in the sun. 



It was a theory of some of the English physicists that the sun had no 

 atmosphere, but was itself a mass of cloud and that the dark spectrum 

 lines were from gases mixed up in the mass. But at an eclipse in 1870 

 Prof. Young saw, in the few moments during which the sun was hidden, 

 the dark lines of the spectrum all change to bright color lines. The 

 same thing was observed in 1871 by others. This proves that the gases 

 lie outside of the body of the sun, and when that body is covered up by 

 the moon, these gases around the outer edge which are not covered by 

 the moon are able to give their own proper discontinuous spectra of 

 bright bands. The hight of this solar atmosphere is 400 to 1,000 miles. 

 In like manner the spectra of many of the stars have .been examined and 

 carefully mapped. The two large stars, Aldebaran in the constellation 

 of the Bull, and Betelguese in Orion, are near each other and so, favorable 

 for comparison. Their spectra show about 70 lines. In that of Alde- 

 baran there are two hydrogen lines, the sodiun line D, magnesium a few 

 lines, calcium four lines, iron four lines, bismuth four lines, tellurium 

 four lines, antimony three lines, mercury four lines. Here we have in 

 this distant star 9 elements, at least, belonging to our earth ; four of 

 which are not found in our sun. Betelguese has the same elements ex- 

 cept the hydrogen* only one other star has been found destitute of 

 hydrogen. It must be observed that the small number of lines which 

 each element registers in these cases is owing to the dimness of the light. 

 It has been shown that as the amount of the material decreases or the 

 intensity of light diminishes by increase of distance, the effect is to drop 

 out lines from the spectrum, but the lines that are left are just as re- 

 liable as far as they go, and perfectly faithful to their positions. Nearly 

 all the stars are found to be like our sun in general, though differing in 

 detail. They all have the continuous colored spectrum crossed by dark 

 lines, but the lines of no two are just alike. It was a question the tel- 

 escope could not settle, whether the bodies called nebulae were really 

 hot, gaseous bodies, or only remote clusters of separate stars. Many 

 such bodies had by the better and larger instruments been so resolved 

 into stars, and it was believed by some that all would be in the course 



