30 Mr. J. N. Lockyer. Comparison of the Spectra of [Dec. 19, 



position of D 3 fty reason of the displacement of D by motion of the 

 ' stars ' in the line of sight. On this point no information is at hand 

 regarding any reference spectrum employed. 



" If, however, it should eventually be established that the line is really 

 D 3 , which probably represents a fine form of hydrogen, it can only be 

 suggested that the degree of fineness which is brought about by tempera- 

 ture in the case of the Sun, is brought about in the spaces between 

 meteorites by extreme tenuity ." 



The observations of Dr. Copeland* have now, I think, established 

 the identity of the yellow line, in the nebula of Orion at all events, 

 with D 3 . In a letter to Dr. Oopeland, I suggested that the line at 

 447 was in all probability Lorenzoni's / of the chromosphere spectrum, 

 seeing that it was associated both in the nebulae and chromosphere 

 with hydrogen and D 3 . This he believes to be very probable. The 

 line makes it appearance in the chromosphere spectrum about 75 times 

 to 100 appearances of D 3 or the lines of hydrogen. 



The association of the line at 447 with D 3 therefore strengthens 

 the view that there is an action in space, away from condensations, 

 whereby matter is reduced to its finest forms. 



Comets. 



Nebulae. 



Probable origins. 



A of probable 

 origins. 





411 



H 



4101 



431 





CH 



431 





434 



H 



434 





447 



? 





468—474 



468—474 



C (hot) 



468—474 





479 



? 





483 





C (cool) 



483 



486 



486-3 



H 



486 





495 



9 





500 



500 



Mg 



500 





509 



? 





517 



517 



C (hot) 



517 



519 





C (cool) 



519 



521 



520 



Mg 



521 



[527] 



527 



Fe 



527 



546 



546 



Pb 



546 





554 



? 





558 



559 



Mn 



558 



561 





C (cool) 



561 



564 





C (hot) 



564 



568 





Pb, Na 



568 





5872 



? (Da) 





The table shows that there are many striking similarities between 

 the two spectra, and there is no doubt that many of the lines are 

 * ' Monthly Notices, E.A.S.,' vol. 48, p. 360. 



