200 LECTUEE ON THE EESULTS OF SPECTRUM ANALYSIS 



line with three dark stellar lines. The conclusion, therefore, appears well founded 

 that another of the constituents of this star is magnesium. 



Again, there are two strong lines peculiar to the element hydrogen; one 

 line has its place in the red part of the spectrum, the other at the blue limit of 

 the green. Both of these correspond to dark lines of absorption in the spectrum 

 of the star. Hydrogen, therefore, is present in the star. 



In a similar way, other elements, among them bismuth, antimony, telurium, 

 and mercury, have been shown to exist in the star. 



Now, in reference to all those elements, the evidence does not rest upon the 

 coincidence of one line, which would be worth but little, but upon the coincidence 

 of a g-roup of two, three, or four lines, occurring in different parts of the spec- 

 trum. Other corresponding lines are probably also present, but the faiutness of 

 the star's light limited our comparisons to the stronger lines of each element. 



What elements do the numerous (jther Imes in the star represent? Some of 

 them are probably due to the vapors of other terrestrial elements, which we 

 have not yet compared with these stars. But may not some of these lines be 

 the signs of primary forms of matter unknown upon the earth ? Elements new 

 to us may here show themselves which form large and important series of com- 

 pounds, and therefore give a special character to the physical conditions of these 

 remote systems. In a similar manner the spectra of terrestrial substances have 

 been compared with several other stars. The results are given in the diagrams. 

 Five or six elements have been detected in Betelgeux. Ten other elements do 

 not appear to have a place in the constitution of this star. 



/? Pcgaisi contains sodium, magnesium, and perhaps barium. 



Siriixs contains sodium, magnesium, iron, and hydrogen. 



a LyrcB ( Vega) contains sodium, magnesium, iron. 



Pollux contains sodium, magnesium, iron. 



About sixty other stars have been examined, all of which appear to have some 

 elements in common with the sun and earth, but the selective grouping of the 

 elements in each star is probably peculiar and unique. 



A few stars, however, stand out from the rest, and appear to be characterized 

 by a peculiarity of great significance. These stars are represented by Betelgeux 

 and /5 Pegasi. The general grouping of the lines of absorption in these stars is 

 peculiar, but the remarkable and exceptional feature of their spectra is the absence 

 of the two lines which indicate hydrogen, one line in the red and the other in 

 the green. These lines correspond to Fraunhofer's C and F. The absence of 

 these lines in some stars shows that the lines and F are not due to the aqueous 

 vapor of the atmosphere. 



We hardly venture to suggest that the planets which may surround these 

 suns probably resemble them in not possessing the important element hydrogen. 

 To what forms of life could such planets be adapted? Worlds without water! 

 A power of imagination like that possessed by Dante would be needed to people 

 such planets with living creatures. 



It is worthy of consideration that, with these few exceptions, the terrestrial 

 elements which appear most widely diffused through the host of stars are pre- 

 cisely eome of those which are essential to life such as it exists upon the earth, 

 namely: hydrogen, sodium, magnesium, and iron. Besides, hydrogen, sodium, 

 and magnesium represent the ocean, which is an essential part of a world con- 

 stituted like the earth. 



We learn from these observations that in plan of structure the stars, or at 

 least the brightest of them, resemble the sun. Their light, like that of the sun, 

 emanates from intensely white-hot matter, and passes through an atmosphere of 

 absorbent vapors. With this unity of general plan of structure, there exists a 

 great diversity among the individual stars. Star differs from star in chemical 

 constitution. May we not believe that the individual peculiarities of each star 



