

1894.] Electrical Interference Phenomena. 349 



lines came into view which were too feeble to be visible on the other 

 photographs. Sulphur is not the only substance which affects this 

 spectrum, for instance, the banded spectrum of magnesia and the 

 spectrum of lime also appear to intensify it. 



It is probable that something similar takes place with regard to 



carbon ; we know that the spectrum is modified by the surrounding 



nitrogen of the atmosphere, and the rays of carbon increase the in- 



! tensity of the nitrogen rays adjacent to the carbon lines, the effect 



: being increased in the case of the spark by a saturated solution of 



zinc or calcium chloride. 



The facts here set forth certainly favour the view that the lines in 



Hartley and Adeney's spectrum of carbon are the lines of the ele- 

 : ment and not merely the edges of cyanogen bands. Finally, I would 

 ' point out that the carbon spectra of Eder and Valenta are not quite 

 ! the same as those obtained by me, for if the photographs published 

 : in the ' Journal of the Chemical Society,' vol. 41, p. 91, are carefully 

 ' examined with a strong magnifier, it will be seen that the graphite 

 1 spectrum, No. 10, on Plate II, yields neither the group III nor 



group IV of cyanogen as depicted in spectrum No. 4 of the photo- 

 1 gravnre plate illustrating Eder and Valenta's paper ; at the same 

 1 time it may also be remarked that it does not resemble the spectrum 



of moistened electrodes to which I have already drawn attention. 



j III. "Electrical Interference Phenomena somewhat analogous 

 to Newton's Rings, but exhibited by Waves along Wires." 

 By EDWIN H. BARTON, B.Sc., late "1851 Exhibition" 

 Science Scholar. Communicated by Professor ARTHUR W. 

 RUCKER, M.A., F.R.S. Received February 20, 1894. 



(Abstract.) 



1. The preliminary paper* on this subject gave the results of a 

 single experiment, and approximately accounted for them by a 

 mathematical theory of the phenomena involved. 



2. The present paper discusses the question of disturbances, and 

 gives nine experiments. Two of these are similar to the first experi- 

 ment, but were made under better conditions ; the others were made 

 either to lead to these improved conditions or in confinnation of the 

 original fundamental conclusions. 



3. The disturbances alluded to arise from the fact that the electrical 

 waves are not suddenly lost after their first incidence upon the ab- 

 normal part of the secondary, but course to and fro until they die out. 

 A method of avoiding the greatest disturbance due to this cause is 



* Boy. Soc. Proc.,' vol. 54, pp. 8596, 1893. 



