August 7, 1890] 



NATURE 



345 



The coincidences here are between the flutings of hot 

 carbon, manganese 558, and lead or sodium 568. D has 

 only been seen bright in one of the stars (y Argus), which 

 is probably one of the hottest ; since D was seen bright in 

 two of the hottest comets, I have inserted it in the list of 

 cometary lines and flutings, and [527] and [579] are added 

 for the same reason. 



Although nine lines or flutings are common to comets 

 and bright-line stars, six occur in comets which do not 

 appear in bright-line stars, and five in bright-line stars 

 which do not appear in comets. 



The apparent absence of hydrogen from comets has 

 already been referred to, as well as the absence of D3. 

 The cool carbon flutings are not seen in the bright-line 

 stars because the temperature is too high, and the line at 

 500 is absent for the same reason ; 521 is probably also 

 absent because of the higher temperature. The lead 

 fluting at 546 may be masked by continuous spectrum 

 in the bright-line stars ; at all events, it appears as an 

 absorption-band when the swarms further condense. 

 Besides the hydrogen and D., lines, the lines 507, 540, 

 and 635 appear in bright-line stars, but not in comets. 



IV. Comparison of Comets and Stars of the Mixed 

 Fluting Group. 



In the Bakerian Lecture I also gave evidence to show 

 that stars of Group II. (Vogel's Class Ill.a) are of a come- 

 tary character, and a little more condensed than the 

 bright-line stars. The ground on which this conclusion 

 was arrived at was the probable presence of bright carbon 

 flutings, in addition to the metallic absorptions. Obser- 

 vations of a Herculis and Mira Ceti by Mr. Fowler at 

 Kensington and by myself at Westgate-on-Sea have fully 

 confirmed this view. The rapid increase of brilliancy of 

 the flutings of Mira at its maximum in 1888 left little 

 doubt in my mind that they were due to carbon, and Mr. 

 Fowler's comparisons showed perfect coincidences with 

 the carbon flutings, with the dispersion of two prisms 

 of 60°. 



Some of the origins which I suggested for the dark 

 bands have also been tested by direct comparisons. 

 Dundr's bands 4 and 5 were found to be coincident with 

 the manganese and lead flutings at 558 and 546 respec- 

 tively, and band 3 was found to be coincident with the 

 manganese fluting about 586. 



Mr. Maunder observed the spectrum of a Ononis 

 on December 16, 1887, and made comparisons with the 

 spectra of carbon, sodium, and manganese, as given by a 

 Bunsen flame. He states the results as follows (" Green- 

 wich Observations," 1887, p. 22) : — " The carbon band at 

 5164 was coincident (within the limits of observation with 

 this dispersion) with the bright space towards the blue of 

 Band VI. (Dun<^r's band 7), and the sodium lines were 

 clearly represented by two dark lines near the middle of 

 Band II. (Duner's band 3), but the two manganese bands 

 observed, not only did not coincide with any great band 

 of the spectrum, but were very far distant from any of 

 them. There were, indeed, faint lines about the neigh- 

 bourhood of either manganese band, but the entire spec- 

 trum is full of such Hnes, and no fluting, nor anything 

 corresponding to one, could be detected near the place 

 of these two bands. A third manganese band was very 

 close to Band II. (Dundr's band 3) of the stellar spec- 

 trum." On the other hand, Vogel measured the position 

 of the sharp edge of a fluting in a Orionis as 559"i, and 

 Dundr's measures for the same vary from 557'5 to 559'3, 

 none of which can be described as " very far distant " 

 from the manganese fluting near 558. Mr. Maunder's 

 observation can only be explained by assuming that the 

 band in question is variable. This might be produced 

 by variations in the intensity of the carbon flutings ; the 

 manganese fluting falls on the carbon fluting near 564, 

 and, according to their relative intensities, the manganese 



NO. 1084, VOL. 42] 



fluting will be visible or will be masked by the carbon. 

 According to Gore, the star was at a minimum in 

 December 1887. 



The fluting near 586 corresponds to Dundr's band 2, 

 for which Duner measures wave-lengths varying from 

 585-4 to 586-1. It apparently escaped Mr. Maunder's 

 notice, at the time he made his observations, that no 

 reference was made in my paper of November 1887 to 

 any band in the star spectra which fell near the third 

 fluting of manganese near 535. The first two flutings, 

 near 558 and 586, fell so near to two of the dark bands 

 in the spectra of the stars of Group II. that there was 

 strong ground for believing them to be due to manganese. 

 This has since been abundantly confirmed by Mr. Fowler's 

 direct comparisons of the manganese flutings with the 

 spectra of several stars of the group. 



Under the heading of "Dundr's Bands" I give the 

 mean wave-lengths measured by Dundr for the dark 

 bands, and the limits of the bright spaces which are due 

 to carbon. 



The figures first given refer to the sharp edges of the 

 flutings ; the other figures indicate approximately where 

 the flutings fade away. 



This comparison shows that there is a very close rela- 

 tion between comets and Group II. independent of the 

 probable origins suggested. Bright carbon flutings, the 

 manganese fluting at 558, the lead fluting at 546, the iron 

 fluting at 615, and the magnesium fluting 521, are 

 common. 



The cool carbon flutings are seen in comets, but not in 

 stars of Group II. the reason being that the temperature 

 is too high. The hot carbon fluting at 564 is in all 

 probability present in stars of Group II., but is always 

 masked, in some cases by continuous spectrum, and in 

 others by the absorption fluting of manganese, which is 

 nearly coincident with it. 



The line, or probably fluting, at 495 has not yet been 

 recorded in comets, but its association with the fluting at 

 500 in Nova Cygni indicates that its apparent absence is 

 entirely due to incomplete observations. 



The second fluting of manganese, near 586, though one 

 of the most prominent in stars of Group II., has not 

 been observed in cometary spectra, probably because 

 there is not sufficient continuous spectrum from the 

 sparse meteor itic background of the comet to produce the 

 absorption of more than the first flutrng of manganese. 



Dundr's band I, 647 to 668, has not yet had an origin 

 assigned to it. J. Norman Lockyer. 



LTo be continued^ 



