191 



Incandescent gases and vapors give off light of certain 

 definite degrees of refrangibility, or they furnish spectra 

 consisting of certain fixed lines ; and these incandescent 

 gases or vapors absorb light of the same degree of re- 

 frangibility as that which they emit. This after all is only 

 the expression in relation to light of the celebrated state- 

 ment made in regard to sound. That a body absorbs all the 

 oscillations which it can propagate. Sound is produced by the 

 vibration of the particles of gravitating matter, whilst light 

 is supposed to be produced by a similar vibration of the 

 particles of a non-gravitating matter called the luminifer- 

 ous ether. 



We are all acquainted with the principle of resonance ; 

 if we sound a given note in the neighborhood of a piano- 

 forte, the string capable of giving out the vibrations pro 

 ducing that note takes up the vibrations of the voice, and 

 we hear it answering the sound. The intenser vibrations 

 proceeding in one direction are absorbed by the string and 

 emitted as waves of slighter intensity in every direction. 



All the bright lines of the spectra, produced by the 

 vapors of known metals, which have yet been examined, 

 appear to be represented by the dark lines of the solar spec- 

 trum. That is to say, dark lines always existing in the 

 solar spectral image, correspond with every line produced 

 by a spectrum obtained by burning iron ; and just so with 

 regard to the other metals which have been examined. 



The conclusion therefore is, that the radiations from the 

 centre of 6ur system — the sun — producing the phenomena 

 of light, heat and actinism, are due to the combustion of me- 

 tallic bodies such as we find on this earth. 



The mass of the sun is, according to this hypothesis, re- 

 garded as being intensely incandescent. Matter, in all re- 

 spects similar to that with which we are acquainted, is 

 undergoing combustion, and of course surrounding the sun 

 with a vaporiform atmosphere, consisting of the emana- 

 tions from the ignited nucleus. But for this atmosphere — 



