reach melting point. These dark lines of absorbed light 

 are called after the name of their discoverer, Professor 

 Frauenhoffer, who first traced their existence in the year 

 1815. 



Experiments conducted with various kinds of gases 

 produced similar Frauenhoffer lines. 



When the newly invented spectroscope was first tur- 

 ned upon our sun, scientists were struck by the mass of 

 dark lines which intersected its spectrum. It became appa- 

 rent that the sun is itself a ball of liquid fire in which 

 all our earthly metals and minerals exist in molten form. 

 A series of systematic spectroscopic researches into the 

 nature of the sun began, under the leadership of Frauen- 

 hoffer, after whom, so far as concerns the extent of their 

 labours, came Kirch off, Bunzen, Brewster and 

 lastly from contemporary scientists Fogel and the Italian 

 savant Sekki. 



Frauenhoffer traced and investigated, with the aid of 

 the microscope, as many as 600 lines in the solar spec- 

 trum. In Brews ter's time as many as 2000 had been 

 discovered, which figure has risen since to no fewer 

 than 5000. 



The greatest number of lines of absorption are found 

 in the red stars, after these in the yellow, to jhe number 

 of which our sun belongs, and the least in the white or 

 blue, such as Sirius on which the lines of hydrogen 

 magnium and natrium are specially prominent. 



The chief value of the spectral analysis lies in the 

 unchanging infallible accuracy of the position occupied 

 by the lines of light. Calium, natrium, copper, iron, 

 coal, once having given their line of light in the spectrum 

 never change the place of their line on experiment, 

 though such experiments should be repeated a million- 

 times ; besides which, combustion on a small scale or a 

 large yields identical results. The lines are always in 

 the same places. 



This quality in the Frauenhoffer lines attracted the 

 involuntary attention not only of astronomers but also 



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