394 



NATURE 



[August 21, 1890 



Planetary nebula 



Nebula in Orion 



Nebula, Gen. Cat., No. 4373. 

 „ ,. n 4234 

 „ „ ., 4390. 



Nebula in Andromeda . . . 



7 Argiis 



Arg.'-Oeltzen, 17681 . . . . 



Lalande, 1 341 2 



1st Cygnus 



2nd Cygnus 



3rd Cygnus 



7 CassiopeicB 



o Ceti". . . 



a Herculis 



a Orionis 



Aurora 



Fluting 468-474- 



469*4 (Copeland) 

 470 (Taylor) . . 



468-474 (Fowler) 



468(Ellery) . . 

 464*6 (Copeland) 

 461-470 (Vogel) 



473 (Pickering) 

 469 (Vogel) . , 



470 (Wolf and Rayet) . 

 465-470 (Vogel) . . . 



468-474 (Fowler) . . . 

 470 (Wolf and Rayet) . 

 464 (Vogel) middle of 



band . 



468-474 (Fowler) . . . 

 470 (Wolf and Rayet) . 

 461-468 (Vogel) . . . 



468-474 (Fowler) . . . 



468-474 (Fowler) . . . 

 468-474 (Fowler) . . . 

 468-474 (Fowler) . . . 



474-478 (Vogel) . . . 



Fluting 517- 



S18 (Vogel) 

 518 (Vogel) 

 518 (Vogel) 

 517 (Fowler) 

 517 (Taylor) 



517 (Fowler) 



517 (Fowler) 



517 (Vogel) 



517 (Fowler) 



517 (Sherman) 



517 (Fowler) 



517 (Lockyerand Fowler) 

 517 (Lockyer and Fowler) 

 517 (Lockyer and Fowler) 



517 (Backhouse) .... 



Copernicus, vol. i, p. 2. 



Monthly Notices, vol. 49, p. 126. 



Bothk. Beob., Leipzig, Heft i, 1872, p. 57. 



„ '.'. ',', V, p'-'ss. 



Roy. Soc. Proc, vol. 45, p. 216. 

 Monthly Notices, vol. 49, 126. 

 Observatory, vol. 2, p. 418. 

 Copernicus, vol. 3, p. 205. 

 Astro- Phys. Obs. zu Potsdam, vol. 4, No. 



14, p. 16. 

 Astr. Nachr., No. 2376. 

 Astro-Phys. Obs. zu Potsdam, vol. 4, No. 



14, p. 17- 

 Comptes rendus, vol. 65, p. 292. 

 Astro-Phys. Obs. zu Potsdam, vol 



14, p. 17. 

 New observations. 

 Comptes rendus, vol. 65 (1867), p 

 Astro-Phys. Obs. zu Potsdam, vol 



14, p. 17- 

 New observations. 



Comptes rendus, vol. 65 (1867), p. 292. 

 Astro-Phys. Obs. zu Potsdam, vol. 4, No. 



14, p. 17. 

 New observations. 

 Astr. Nachr., No. 2691. 

 New observations. 

 New observations. 

 New observations. 

 New observations. 



Bothk. Beob., Leipzig, Heft I, 1872, p. 43. 

 Nature, vol. 7, p. 463. 



No. 



292. 

 4, No. 



We have now to inquire into the previous work on this 

 subject. 



Carbon in Stellar Spectra. 



Secchi, in 1869, was the first to call attention to the 

 possible existence of indications of carbon in stellar 

 spectra in connection with stars of his types IIL and IV.^ 

 He even compared the spectrum of 152 Schjellerup with 

 the carbon spectrum obtained from benzene. His micro- 

 metric measures of the distances of the principal bands 

 in the two spectra from the sodium line D gave great 

 weight to his statement.^ 



But although Secchi observed the coincidence of the 

 edges of two dark bands in his types IIL and IV., and 

 remarked that the light-curve in one case faded towards 

 the red, and in the other towards the violet end of the 

 spectrum, he did not recognize that we were dealing with 

 radiation in one case and absorption in the other. 



Indeed, Secchi regarded type IV. as presenting chiefly 

 radiation phenomena, for later,-' when writing with 

 respect to stars of this type he states : — 



" Quelques-unes des raies noires et les plus importantes, 

 coincident k tres-peu-pr^s avec celles du troisieme type ; 

 cependant le spectre, dans son ensemble, se presente comme 

 un spectre direct appartejiant a un corps gazeuv, plutot que 

 comme un spectre d'absorption. Si on le'considere comme 

 un spectre d'absorption, on trouve qu'il presente le carac- 

 tere des composes du charbon, tels qu'on les obtient en 

 produisant une serie d'etincelles electriques dans un 

 melange de vapeur de benzine et d'air atmospherique et 

 dans Tare voltaique entres les charbons." 



From the foregoing, it is evident that Secchi had ob- 

 served the coincidence of the flutings of carbon with the 

 dark flutings in stars in his fourth type, but missed the 

 significance of it altogether. 



^ AttidelV Acad, de' Niiovi Lincei. xxv., 1S72. 



- These and other comparisons led Secchi to n ne : — "La conclusione e che 

 nelle stelle di_40 tipo vi e certo il carbonio in una combinazione di debole 

 tensione coU' idrogeno, e ch; questa combinazione esiste nello stesso stata, o 

 in altro prossimo anche in quelle di 30 tipo." 



3 "Le Sjle.l," vol. ii. p. 458. 



Dr. Huggins, however, in a footnote to the first edition 

 of Schellen's " Spectrum Analysis," edited by him, gave 

 an observation of his of the spectrum of 152 Schj., and a 

 diagram of the spectrum of this star, which combated 

 Secchi's work. In his words : — 



" He compared the spectrum of the star, using 

 a narrow slit, with the bright lines of sodium and 

 carbon. The line marked D he found to be co- 

 incident with that of sodium. The less refrangible 

 boundary of the first of the three principal bright bands 

 in the spectrum of carbon is nearly coincident with the 

 beginning of the first group of dark lines ; the second of 

 the carbon bands is less refrangible than the second 

 group in the star ; the third band of the carbon spectrum 

 falls on the bright space between the second and third 

 group of dark lines in the spectrum of the star. The ab- 

 sorption bands are therefore not due to carbon." 



Vogel, in 1884, showed that Dr. Huggins's observations 

 were inaccurate ; that the bands really did coincide with 

 the carbon bands ; and that Secchi's statement was per- 

 fectly correct with regard to this star (152 Schjellerup).^ 



' " Neben dem Spectrum des Natriums erschienen noch ganzschwach zwei 

 Banden d«;s Alkohol-spectrums, die vollkommen mit den dunklen Bandendes 

 Sternspectrums zu coincidiren schienen. Der Anfang der ersten Bande des 

 Alkoholspectrums wurde zu -f- 14' 37'' gemessen. Auf den Anfang der 

 zweiten Bande wurde wlederholt der Faden gestellt, und coincidirte jedesmal 

 der Faden so vollkommen als moglich mit der Bande im Sternspectrum. 

 Auch directe Vergleichungen zwischen Alkoholspectrum und Sternspectrum 

 konnten gemacht werden, da das Sternspectrum hell genug war und sich 

 ganz gut von den das ganze Gesichtsfeld durchsetzenden mattleuchtenden 

 Banden des Alkoholspectrums abhob." Following some measures made on 

 June I, it is noted : — " Bei den Vergleichungen rait dem Natrium- und Alko- 

 holspectrum wurde wiederholt die Ueberzeugung gewonnen, dass eine Coinci- 

 denz mit den Natrium-Linien, sowie mit den beiden starksten Banden des 

 Kohlenwasserstoffspectrums im Spectrum der Flammen und des Sternes 

 stattfand. Ich setzte an diesem Abend, da der Himmel besonders gunstig 

 war, noch das stark zerstreuende Kutherfurd'sche Prisma ein und konnte 

 damit wenigstens die beiden starksten Banden im Sternspectrum messen und 

 wiederum durch directe Vergleichung die absolute Coincidenz der hellsten 

 Bande des Kohlenwasserstofifspectrums mit einer Bande des Sternspectrums 

 beobachten." In summing up the observations of the spectrum of this star 

 Prof Vogel remarked, " Vergleicht man diese Beobachtungen mit den Seite 

 14 angefiihrten des Kohlenwasserstoffes, so ergiebt sich zweifellos das Vor- 

 handensein von KohlenwasserstofF in der Atmosphare des Sternes." — " Astro- 

 physikalischen Observatoriums zu Potsdam," No. 14, p. 23, 1884. 



NO. 1086, VOL. 42] 



