June 14, 1900] 



NATURE 



163 



group of two carbon-bands, usually accompanied by a preceding 

 one close-following the gas-flame spectrum's blue beam, near the 

 Fraunhofer rays h, H, at the vjolet confines of the visible spec- 

 trum. All three are seen brightly in the spectrum of the electric 

 arc between carbon poles, where the furthest member of this 

 blue, violet, and ultra-violet array produces a just ocularly visible 

 pharos-V\V.^ mass of grey-looking light slightly beyond the spec- 

 trum-place of the furthest visible pair of dark lines H, K, of the 

 solar spectrum. This strong outlying pair and its near preceding 

 blue band were referred by Profs. Liveing and Dewar,^ and 

 also, when he found the two chief bands bright by themselves in 

 hisspectrum photographs of the Comet i88l. III., by Sir William 

 Huggins,- to cyanogen. But the same strong pair's violet, 

 or first colonnade, between G and h, when he first traced it 

 beautifully distinct and bright with the ordinary coil-spark in an 

 end-on marsh-gas vacuum-tube,' was coupled on by Prof. Piazzi 

 Smyth, in his " Measures of Gaseous Spectra with High Dis- 

 persion," 1884, as it was also grouped by Dr. W. M. Watts 

 in his " Index of Spectra," 1872 (and where Sir J. N. Lockyer 

 classed all these three flutings provisionally together,'* from a 

 careful survey made in 1880^ of their deportments, in an un- 

 stable-systemed extension, " B," of the " hot carbon's " ordinary 

 set of flutings, "A"), as a sixth or extra fluted-band transcend- 

 ing in refrangibility all the five commonly seen ones of the 

 " hydrocarbon," or blue gas-flame series. 



Six of the seven main lines of the blue band of this set were 

 marked as measured lines distinctly, by Prof. Piazzi Smyth, in a 

 hazy glow of light immediately following the fourth, or blue 

 band of his "High Dispersion Spectrum" Paper's full-length map 

 of the "hydrocarbon" spectrum, but as considerably weaker 

 lines than those of the violet or "marsh-gas" band. As the 

 blue band, however, is in fact the weakest one of a group of 

 bands which only the exceedingly hot flame of cyanogen, or the 

 intense heat of the electric arc, or jar-spark usually produces, its 

 exact indication there, precisely in its natural inferiority of 

 strength to the violet array, and with only one line missing of its 

 seven, at the beginning of the hazy glow, is a speaking testimony 

 to the faithful accuracy of the late Prof. Piazzi Smyth's spec- 

 trum records, as well as to the watchful care with which all the 

 spectra which he mapped were guarded against contaminating 

 admixtures of interloping gas-spectra ; since with the modest 2-3 

 inch sparks which he was content to use, of a simple induction 

 coil, nothing but the lamp-like brightness of the Salleron and 

 Casella end-on tubes examined, and the chemical purity of the 

 contents of those used in taking final spectrum measures, could 

 have been expected to show the weakest of the three "cyano- 

 gen " bands so equally free from other spectrum -glares, and 

 almost as sharply well-defined in position, as its bright violet 

 companion tier of " marsh-gas " lines was seen and measured. 



The fifth (faint violet) band — or the latter part of it — seen 

 under high dispersion to contain only hazy linelets, with no 

 strong lines or sharp-edged flutings, is the only visible light-beam 

 in the Bunsen-flame spectrum which Sir J. N. Lockyer seems 

 willing to admit," can be described correctly as a "hydra- 

 carbon " band ; and in his splendid series of discriminations of 

 celestial spectra, that brightest portion of the Bunsen flame's 

 violet band forms the whole system of spectroscopic bands which 

 in those analyses of celestial spectra is usually indicated as 

 characteristically denoting hydrocarbon radiation. Two small 

 bands, or fluted line-groups, however, sometimes occur also in 

 this unstable violet, or "Carbon-B" region, of which one is 

 classed by Sir J. N. Lockyer together with the pharos-XxV^ band 

 beyond H, K, as an invariable accompaniment (much moie re- 

 frangible than the four " Carbon-A " bands) of the "hot-carbon " 

 spectrum. This small three-lined band falls exactly in place 

 and width on the Bunsen-flame spectrum's fifth, or violet band's 

 preceding zone of weak hazy light, as the late Prof. Piazzi 



1 " On the Spectra of the Compounds of Carbon with Hydrogen and 

 ""itrogen." Two Papers, Nos. i., ii. Proceedings of the Royal Society, 

 XXX. p. 152 and 494, February-June, 1880. 

 Proceedings of the Royal Society, vol. xxxiii. p. i, November 1881. 



■ It was also seen by Dr. VV. M. Watts (" On the Spectrum of Carbon," 

 Nature, vol. xxiii. p. 197, December, 1880), "very bright" in a pure 

 Marsh-gas vacuum-tube ; and in a methyl vacuum-tube by Dr. Pliicker. 



*_The Bakerian Lecture, " Suggestions on the Classification of the 

 various Species of Heavenly Bodies," — " Radiation Flutings " : Proceedings 

 of the Royal Society, vol. xliy. p. 53, April, 1888 ; and " Appendix to the 

 Bakerian L.ecture," Section vi. " General Statement with regard to Carbon," 

 Proceedings o^ the Royal Society, vol. xlv. p. 186, November, 1888. 



' " Further Note on the Spectrum of Carbon," Proceedings of the Royal 

 Society, vol. xxx. p. 461, May, 1880. 



8 " Researches on the Spectra of Meteorites," Proceedings of the Royal 

 Society, vol. xliii. p. ii8 ; November, 1887. 



Smyth, in his full-length map and micrometric measures of that 

 spectrum pictured it, surrounding the place of the violet line 

 H7 almost as closely as its bright following "hydrocarbon" 

 light-zone surrounds the dark solar line G's position, with a 

 curiously prominent solitary bright line in the dark partition 

 space between them. A fairly satisfactory explanation of this 

 fifth band's construction might thus, with no material need of 

 any reconciling adjustment to the "Carbon-B" band's line- 

 places, be extracted from the Edinburgh spectrum record, by 

 supposing the first and second portions of its divided light-field 

 to belong really to different radiant sources, and to be due, in- 

 dependently of each other, respectively to " hot carbon " and to 

 " hydrocarbon gas's" incandescence. But the near agreement 

 in position between the flame-band's feeble front-domain of 

 shapeless light-haze, and the " hot carbon's " small three-ribbed 

 fluting lacks far too much from being well afifirmed by exact co- 

 ordinations to be any certain evidence of a real spectroscopic or 

 physical connection ; and the weak preceding portion of the 

 violet flame-band has thus been very appropriately consorted by 

 Sir J. N. Lockyer with the following bright portion of this 

 violet haze-band, as belonging both together to the hydro- 

 carbon spectrum.^ Another small violet-region band was traced 

 by Sir W. Huggins in the spectrum of the Comet 1881, III., 

 where it lay between the violet and the ultra-violet " cyanogen " 

 bands, a little beyond h towards the line H of the solar 

 spectrum. 



Among this "Carbon-B" suite of bands, suspected by Sir 

 J. N. Lockyer at an early stage of his spectroscopic observations 

 of the sun, in 1874, to have counterparts in the dark lines of the 

 solar spectrum, the strong pharos A^^t. ultra-violet fluting's deli- 

 cate train of bright lines and linelets was at length photographic- 

 ally proved by Sir J. N. Lockyer, in 1878,^ to coincide precisely 

 with a close-packed orderly array of faint, exceedingly fine dark 

 lines at the same place in the solar spectrum ; and the same 

 coincidence of about thirty serrations of this band in ten 

 Angstrom's wave-length units, with as many exactly correspond- 

 ing ripplings of light and darkness at the ultra-violet confines of 

 the sun's visible spectrum was again very abundantly well 

 proved by Profs. Trowbridge and Hutchins at Hartford, U.S., 

 in 1887.3 It was also pointed out by Profs. Liveing and Dewar 

 at the close of the second of their above-quoted papers, in 1880, 

 on the ' ' Spectra of Compounds of Carbon with Hydrogen and 

 Nitrogen," that a fluted ultra-violet band in the spectrum of the 

 cyanogen-flame, of which they photographed many in an ultra- 

 violet region extending far beyond this grey one's position, 

 exactly coincided in spectrum-place with the remarkably fluted 

 ultra-violet dark band P, in the solar spectrum. After Sir W. 

 Huggins and Padre Secchi had independently detected the 

 "hydrocarbon's" or low gas-flame's bands in the spectrum of 

 Winnecke's Comet, in 1868, and some ten or twelve comets in 

 as many following years were found to show the same bands in 

 their spectra,'* together with occasional traces of the oxy-carbon 

 or "cool-carbon " spectrum, a far wider range of the " hot " and 

 " cool carbon " bands was presently discovered for them by Sir 

 J. N. Lockyer among the spectra of celestial bodies, and in his 

 " Researches on the Spectra of Meteorites," in 1887,^ and in 

 the Bakerian Lecture to the Royal Society on a " Suggested 

 Classification of the various Species of Heavenly Bodies," ' the 

 low gas-flame's or hot carbon spectrum's bands were clearly 

 shown to exhibit themselves, with rarer excrudescences of cool 

 carbon bands, not only in comets, but alike in sun-like and 

 fluted, and bright-line and temporary stars, and even in nebulae, 

 the aurora, and sometimes in lightning-flashes, as a sort of torch- 

 light glow of colliding meteorites, condensed meteoritic swarms, 

 and electrically gasified and illumined meteoritic dust, through- 

 out the universe. 



It surely needed then only the recent discovery by Prof. G. E. 

 Hale and his coadjutors, Mr. W. S. Adams and Prof. Frost, in 



1 The Bakerian Lecture :— " Radiation Flutings," Proceedings of t^e 

 Royal Society, vol. xliv. p. 53, April 1888. 



2 " Note on the existence of Carbon in the Coronal Atmosphere of the 

 Sun," Proceedings o( ihs Royal Society, vol. xxvii. p. 308, April, 1878. 



3 "On the Spectrum of Carbon compared with that of the Sun," Proceed- 

 ings of the American Academy of .\rts and Sciences, vol. xxiii. p. 10, 1887-8 ; 

 and American Journal of Science, Series 3, vol. xxxiv. p. 345, 1888 ; 

 Nature, vol. xxxvii. p. 114, December, 1887. 



* "The Meteoritic Hypothesis," by Sir J. N. Lockyer (Macmillan and 

 Co., 1890), p. 176 :— Table of Carbon-Spectrum Comets. 



''> Proceedings ai the Royal Society, vol. xliii. pp. 117-156, November, 

 1887. 



8 Proceedings of the Rojfal Society, vol. xliv. pp. 1-93, April, 1888 ; and 

 ("Appendix to the Bakerian Lecture ") vol. xlv. pp. 157-262, November, 



NO. 1598, VOL. 62] 



