72 



Mr. J. N. Lockyer. On a Sun-Spot. 



Nov. 25, 



III. " On a Sun-Spot observed August 31, 1880." By J. N. 

 Lockyer, F.R.S. Received October 26, 1880. 



The recent activity in solar spots has enabled me to test the hypo- 

 thesis I put before the Society on December 12th, 1878, by observing 

 whether the velocity of the up-rush or. down -rush of the so-called 

 iron vapour in the sun was registered equally by all the iron lines, as 

 it should be on the received hypothesis. 



The observations already made, though few in number, indicate 

 that while motion is shown by the change of refrangibility of some 

 Knes, other adjacent lines indicate a state of absolute rest. Thus, in 

 an observation of a sun-spot on August 31st, 1880, when the iron line 

 at 5207'6 was doubly contorted, indicating an ascending and descend- 

 ing velocity of about fifteen miles a second, the two adjacent iron 

 lines at X 5203*7 and 5201' 6, visible in the same field of view, were 

 unaffected. 



I send this paper to the Royal Society with all reserve, in order to 

 call the attention of other observers to the point, as I fear it is only 

 too probable that foggy weather will stop all observations here. 



IV. " On Methods of Preparing Selenium and other Substances 

 for Photophonic Experiments." By Professor Graham 

 Bell. Communicated by the President. 



[Publication deferred.] 



