38 



Spectra of Nebula, Stars, Comets, and Aurora?. [Dec. 19, 



brought together and compared. It is not sufficient to show that 

 each resembles comets in some respects, as each one might have some 

 feature which was absent in the other. I, therefore, give the 

 following table to show how far they resemble each other. In the 

 last column the dark bands which are simply due to absence of 

 radiation, and are not really absorption-bands, are omitted. 



Nebulae. 



Aurora. 



Comets. 



\-\ v»i nth f . lino 

 J_>I It* IlL-l illt? 



ObdiXo W 11/11 lillJLcU. 

 flnf 1 n fife 



4101 







411 



— 



4101 







— ■ 



426 



[426] 









— 



431 



431 



— 



449 (bright space) 



434 



435 



— 



434 



— 



447 



— 



— 



— 



— 



— 



— 



— 



— 



461 — 451 bright 



468—474 



474 — 478 



468 — 474 



468 — 474 



472—476 „ 



479 



482 



483 



— 



— 



486 



486 



486 



486 



— 



4958 



— 



— 



— 



4958 — 486 bright 



500 



500 



500 





502 — 4959 dark 



509 







o(J7 





517 



517 



517 



517 



516—502 bright 





519 



519 







520 



522 



521 





522—516 dark 



— 



— 



— 



— 



524—527 dark 



527 





[527] 



527 







531 







— 





535 











539 





540 





546 



545 



546 





544—551 dark 



554 











559 



558 



558 



558 



559—564 dark 







561 











564 



564 









568 



568 









[579] 



579 













585—594 dark 



5872 (D 3 ) 







5872 







606 



[589] 



589 







620 



[615] 





616—630 dark 





630 





635 





It will be seen that there are three flutings which run through the 

 five columns, namely, 468 — 474, 517, and 558 ; and four more, H 486, 

 Mg500, Mg521, and Pb 546, occur in four out of the five columns. 

 Out of the thirty-four lines or flutings given, there are nineteen 

 which occur in less than three columns, but this number is greatly 

 reduced when slight differences of temperature, masking effects, and 

 the exceptional conditions of comets are taken into account. 



It is now univ3rsally agreed that comets are swarms of meteorites, 



