354 FRAGMENTS OF SCIENCE 



give us the bands of our terrestrial metals, it is a decla- 

 ration on the part of these orbs that such metals enter 

 into their composition. Does the sun give us any such 

 intimation? Does the solar spectrum exhibit bright lines 

 which we might compare with those produced by our ter- 

 restrial metals, and prove either their identity or differ- 

 ence? No. The solar spectrum, when closely examined, 

 gives us a multitude of fine dark lines instead of bright 

 ones. They were first noticed by Dr. Wollaston, but were 

 multiplied and investigated with profound skill by Fraun- 

 hofer, and named, after him, 'Fraunhofer's lines. They 

 had been long a standing puzzle to philosophers. The 

 bright lines yielded by metallic vapors had been also 

 known to us for years; but the connection between both 

 classes of phenomena was wholly unknown, until Kirch- 

 hoff, with admirable acuteness, revealed the secret, and 

 placed it at the same time in our power to chemically 

 analyze the sun. 



We have now some difficult work before us. Hitherto 

 we have been delighted by objects which addressed them- 

 selves as much to our aesthetic taste as to our scientific 

 {acuity; we have ridden pleasantly to the base of the final 

 cone of Etna, and must now dismount and march through 

 ashes and lava, if we would enjoy the prospect from the 

 summit. Our problem is to connect the dark lines of 

 Fraunhofer with the bright ones of the metals. The white 

 beam of the lamp is refracted in passing through our two 

 prisms, but its different components are refracted in differ- 

 ent degrees, and thus its colors are drawn apart. Now, 

 the color depends solely upon the rate of oscillation of the 

 atoms of the luminous body; red light being produced by 

 one rate, blue light by a much quicker rate, and the col- 



