seen on the Sun's Limb during a Total Eclipse. 303 



solar spots, some of which appeared on the suit's disk in places 

 not far removed from those occupied by the red flames ; and Mr. 

 H. F. Talbot suggested that the latter might be heated vapours, 

 which, rushing through the spots or openings in the sun's pho- 

 tosphere, ascend to the upper regions of the solar atmosphere 

 in names of immense elevation. 



The third and most recent occasion on which these protube- 

 rances were observed, was during the total solar eclipse of 

 July 18th, 1860, which was attentively watched in Spain by 

 eminent men from all quarters. It was on this occasion that 

 Mr. De la Rue was enabled, by means of the Kew heliograph, to 

 obtain a photographic representation of them ; and from the 

 nature of his observations, as well as from the very great care 

 and labour which he has bestowed upon their reduction, no doubt 

 -can be entertained of the accuracy of his conclusions. 



By his labours, and by those of Mr. Airy and other observers, 

 it is rendered certain that these prominences belong to the sun, 

 and that they are not optical illusions, but represent actual 

 changes of unknown nature but of stupendous magnitude taking 

 place in our luminary, and extending in some instances to a di- 

 stance of 70,000 miles or more above the photosphere of the sun. 

 It was also proved on this occasion that the light from the 

 protuberances was unpolarized, and that it had very great actinic 

 power. Many members also of the expedition supposed these 

 appearances to be clouds in the solar atmosphere, to which idea 

 they may have been led by the circumstance that at least one 

 mass appeared to be floating quite detached, 14,000 miles from 

 the body of the sun. Mr. De la Rue also seemed to think that 

 one of the most remarkable of the protuberances was connected 

 in position with a mass of faculae which came round upon the 

 sun's disk a day or two afterwards. 



These are the three occasions on which these phenomena have 

 been observed ; and it has been the nearly unanimous belief of all 

 observers who have acknowledged their connexion with the sun, 

 that they represent great disturbances taking place in those 

 regions of the solar atmosphere in which they manifest themselves. 

 Since, therefore, these are phenomena undoubtedly associated 

 with our luminary, since also they extend to a distance of at 

 least 70,000 miles above the sun's photosphere, and since we 

 cannot well conceive them to exist without the presence of an 

 atmosphere of some sort, however attenuated, we are led to the 

 startling conclusion that the sun's atmosphere extends to at least 

 this distance above its surface. 



This conclusion certainly excites a feeling of wonder in the 

 mind, which admits so strange a result with reluctance ; and this 

 has induced the writer to seek for an explanation of these ap- 



