124 THE CHEMISTRY OF THE SUN. [CHAP. 



where it changed its refrangibility towards the blue end of the 

 spectrum, we had an enormous patch of light. 



An observation which I made in April, 1870, 1 pointed un- 

 mistakably to a connection between these bright regions or 

 lozenges, as I called them, and the prominences. On ex- 

 amining the F line, I found that the bright chromospheric 

 line not only intruded very much more than it generally did 

 on to the disc, but that close to it I saw one of those bright 

 lozenges to which reference has just been made, the dark 

 hydrogen absorption appearing over it. Gradually this lozenge 

 travelled very nearly to the edge of the sun, and before it got 

 quite to the edge, I saw a tremendous contortion of the F line, 

 that line being deflected first violently to the violet, and then 

 as violently to the red end. Also, in the same locality, I saw 

 the F line broken into two parts it was doubled. And what 

 was going on while this was happening ? A prominence, 

 obviously with its root some distance from the limb, had 

 gradually travelled beyond the limb ; in appearance it became 

 very much more elevated, and seemed, as it were, in perspective 

 over the limb ; but what I saw first was very rapidly changed. 

 I was not observing with an open slit, so I at once coined the 

 term, " motion forms," because the forms observed did not in 

 any way represent the shape of the prominences. 



The publication of these observations gave rise to much 

 discussion. Professor Eespighi attributed the phenomena to 

 disturbances in our air, or to the action of the heat of the sun's 

 image on the slit, apparently forgetting that such a cause would 

 affect all the lines in the spectrum, and not a few isolated ones 

 only. In a subsequent memoir he admits having himself seen 

 the phenomena. Father Secchi also for a long time discredited 

 it, but eventually admitted that he had seen the phenomena. 

 Another observer referred to my observations on the changes 

 in question as " les illusions de Mr. Lockyer " ; but Professor 



1 Proc. Roy. Soc. No. 120, 1870. 



