1887.] 



Researches on the Spectra of Meteorites. 



141 



ble than fr 4 — this is the high-temperature spectrum — and the other — 

 the low-temperature spectrum — with a fluting just less refrangible 

 than h v it is at once suggested that sudden changes in comets may 

 very likely be accompanied by a transition from one condition of 

 carbon vapour to the other, so that on this account apparent discre- 

 pancies in the measurements of the same comet at different times 

 may present real facts. Then again we have the motion of the swarm 

 along its orbit, which in some cases we know is comparable to the 

 velocity of light, so that variations of wave-length are produced as 

 indicated in comet 1882. We also have the possibility that the 

 velocity of the vapours in the jets, and that due to the electric repul- 

 sion — which, according to Zollner's view, is the origin of comets' 

 tails — may also produce changes of refrangibility. 



Although as a rule the bright fluting seen in comets appears to be 

 that due to high temperature, this is apparently not always the case. 

 In the experiments on the glow of magnesium wire, the flutings of 

 carbon have always been seen, and when the vacuum is approached 

 the flutings have been those of the low-temperature spectrum. When 

 the glow of the metal is seen under certain conditions, mixed with 

 carbon vapour, \ and b 2 are seen as bright dots or short lines inside 

 the carbon fluting, exactly as they were observed, probably, by 

 Huggins in Brorsen's comet ('Roy. Soc. Proc.,' vol. 16, p. 386). 



Authorities used in the Maps. 



The map showing the bright lines in Stars is based upon the fol- 

 lowing authorities :- — 



3rd Cygnus, B.D. +36°, No. 3956, E.A. 20 h. 10 m. 6 s., Decl. +36° 18'. 



Vogel. — ' Publicationen des Astrophysikalischen Observatoriums zu Potsdam,' 

 vol. 4, No. 14, p. 19. 

 2nd Cygnus, B.D. +35°, No. 4013, E.A. 20 h. 7 m. 26 s., Decl. + 35° 50-8'. 



Vogel. — ' Publicationen des Astrophysikalischen Observatoriums zu Potsdam,' 

 toI. 4, No. 14, p. 19. 



Wolf and Eayet — ' Comptes Kendus,' toI. 65 (1867), p. 292. The wave- 

 lengths were obtained from a curve based on the measurements given. 

 Argelander-Oeltzen 17681, E A. 18 h. lm. 21s., Decl. -21° 16'2'. 



Vogel.—' Publicationen des Astrophysikalischen Observatoriums zu Potsdam,' 

 vol. 4, No. 14, p. 15. 



Pickering. — ' Astronomische Nachrichten,' No. 2376. 



Pickering. — ' Observatory,' vol. 4, p. 82. 

 7 Argus, E.A. 8h. 5 m. 56 s., Decl. -46° 59'5'. 



Copeland. — ' Copernicus,' vol. 3, p. 205. 



Ellery.— ' Observatory,' vol. 2, p. 418. 

 Stone 9168 (star in Scorpio), E.A. 16 h. 46 m. 15 s., Decl. -41° 37-6'. 



Copeland. — ' Copernicus,' vol. 3, p. 205. 

 1st Argus, E.A. 8 h. 51 m. 1 s., Decl. -47° 8'. 



Copeland. — ' Copernicus,' vol. 3, p. 206. 

 2nd Argus, E.A. 10 h. 36 m. 54 s., Decl. -58° 8'. 



Copeland. — ' Copernicus,' vol. 3, p. 206. 



