50 Mr. I\. Meldola on a Cause for the Appearance 



deafness may be relieved. For telephony articulation has 

 become perfect, and the loudness increased. Duplex and mul- 

 iiplex telegraphy will profit by its use ; and there is hardly a 

 science, where acoustics has any direct or indirect relation, 

 which will not be benefited. And I feel happy in being able 

 to present this paper on the results obtained by a purely phy- 

 sical action to such an appropriate and appreciative body as 

 the Physical Society. 



In conclusion, allow me to state that throughout the whole 

 of my investigations I have used Prof. Bell's wonderfully sen- 

 sitive telephone instrument as a receiver, and that it is owing 

 to the discovery of so admirable an appliance that I have been 

 enabled to commence and follow up my researches. 



VI. On a Cause for the Appearance of Bright Lines in the 

 Solar Spectrum. By Raphael Meldola, F.R.A.S., F. C.S. } 

 8fc* 



IN July 1877 Professor Henry Draper showed that oxygen 

 and (probably) nitrogen are present in the sun's atmo- 

 sphere, the spectral lines of these gases appearing as bright 

 lines in the solar spectrum. 



The photograph accompanying Professor Draper's paper f 

 shows that the oxygen-lines are bright, although not conspi- 

 cuously so, upon a less-luminous background. 



The discoverer of this most important fact in solar chemistry 

 does not offer any complete explanation of the exceptional 

 behaviour of the lines of these elements, but remarks that " it 

 may be suggested that the reason of the non-appearance of a 

 dark line may be that the intensity of the light from a great 

 thickness of ignited oxygen overpowers the effect of the pho- 

 tosphere, just as, if a person were to look at a candle-flame 

 through a yard thickness of ignited sodium- vapour, he would 

 only see bright sodium-lines and no dark absorption-lines. 

 Of course such an explanation would necessitate the hypo- 

 thesis that ignited gases such as oxygen give forth a relatively 

 large proportion of solar light." 



The oxygen-spectrum referred to in the above-mentioned 

 paper is the well-known "line spectrum" seen when powerful 

 disruptive sparks pass through the gas. Dr. Schuster has 

 recently succeeded in obtaining a second or " compound" 

 spectrum of oxygenf, the fundamental lines of which he has 



* Communicated by the Author. 



t Nature, vol. xvi. p. 3G4, August 30, 1S77. 



X Nature, vol. xvii. p. 148, December 20. 1877. 



