360 THE CHEMISTEY OF THE SUN. [CHAP. 



the reversing layer for a moment, for, when it comes to be examined, 

 we shall probably find that scarcely any of the Fraunhofer lines 

 owe their origin to it, and we shall have a spectrum which is not a 

 counterpart of the solar spectrum." 



I followed up this address to the Astronomical Society by 

 the following memorandum, which I laid before the Solar 

 Physics Committee : 



"The total eclipse of the sun which takes place in May next year 

 will be visible in such an accessible region, that it is to be hoped 

 that the precedents of 1860, 1870, 1871, and 1875, will be followed 

 and steps taken to secure observations, the more especially as the 

 eclipse will happen somewhat near to the period of maximum sun- 

 spots, and will allow of a comparison being made with the results 

 obtained in India in 1871. 



" There is one new point (it is not necessary now to refer to the 

 importance of registering the ordinary phenomena) to which I beg 

 to invite the attention of the Committee. 



" The discussion of the sun-spot spectra recently observed at 

 Kensington, and of the prominence spectra observed at Palermo by 

 Tacchini, since 1872, throws some doubt upon the validity of some 

 of the conclusions based upon the results obtained by the English 

 and American Government Eclipse Expeditions in 1870. 



" In that year, at the moment of the disappearance of the sun, 

 a large number of bright lines was seen to flash out, and it was 

 supposed that these lines composed the spectrum of a thin layer 

 near the sun, and were those the reversal of which produced the 

 lines of Fraunhofer. 



" Hence this layer has been termed, and generally accepted to 

 be, the reversing layer. The conclusion seemed to be in harmony 

 with the results obtained by Dr. Frankland and myself, who gave 

 reasons for showing that the region in which the absorption of the 

 elementary bodies of greater atomic weight than hydrogen, mag- 

 nesium, and sodium, must be below the chromosphere. This view 

 was put forward at a time when the elementary nature of the 

 so-called elements was never questioned and before any of the 

 recent results had been obtained. 



