1880.] Note on the History of the Carbon Spectrum, 



491 



the poles, and the final clause added in the published paper accords 

 with it. 



There is no inconsistency between the opinion there expressed and 

 that subsequently given in the paper " On the Spectra of the Com- 

 pounds of Carbon with Hydrogen and Nitrogen;" and that such a 

 charge could have been made is due only to Mr. Lockyer's having quoted 

 the uncorrected proof . 



To come to the omissions we have made in reference to the work of 

 others. The complaints appear in such remarks as the following, 

 which we extract from Mr. Lockyer's paper : — 



"As Messrs. Liveing and Dewar do not controvert the very definite 

 conclusions arrived at by Attfield, Morren, Watts, and others, I can 

 only presume that they have taken for granted that the experimental 

 work performed by these men was tainted by the^ presence of • impuri- 

 ties, and that it was impossible to avoid them." 



" The only reference to this admirable work, in which vacuum tubes 

 and the electric discharge were largely employed, which I can find in 

 Messrs. Dewar and Liveing's paper is the following : — " The spectrum 

 of hydrocarbon burning in air has been . . . described .... by 

 Attfield." 



It was not our intention to give a complete historical account of 

 what had been done previous to the date of the paper by Angstrom and 

 Thalen ("Nov. Acta Reg. Soc. Upsal.," 1875),* as in that paper they had 

 discussed the observations of experimenters who had been engaged on 

 this subject before that time. Nor had we any desire to avoid or con- 

 trovert, or take anything for granted, in the work of early investiga- 

 tors. We merely passed over for the sake of brevity such work as had 

 not stood the test of subsequent investigation. We could hardly accept 

 Dr. Attfield' s work, however good for its time, as authoritative, seeing 

 that his experiments were made, as he allows (" Phil. Mag.," 1875), with 

 very imperfect appliances, and evidently without Ms being so well 

 aware as we now are of the nicety required in regard to the purity of 

 his materials. In fact, he found no distinction between the spectrum 

 of carbonic oxide and that of hydrocarbons, and found the lines of 

 nitrogen in the spectrum of the flame of cyanogen. 



We can hardly be charged with ignoring Morren's work, for we 

 have referred to it again and again. The particular passage quoted 

 by Mr. Lockyer embodies observations and conclusions which are at 

 variance with those of Pliicker and Hittorf, as well as of Watts ; and 

 are substantively discussed by us in our paper. 



Dr. Watts' position with reference to this subject deserves very 

 special consideration, as he has perhaps directed his attention to it 

 more continuously and laboriously than any other investigator. And 

 as his publications have extended over a long period of years, it is 

 clear that a grave injustice is done him if his early work be selected 



