PROCEEDINGS 



OF 



THE ROYAL SOCIETY. 



"On the Physical Constitution of the Sun and Stars''*. By G. 

 Johnstone Stoney, M.A., F.R.S., F.R.A.S., Secretary to the 

 Queen's University in Ireland. Received May 15, 1867. 



Part I. Of the Sun. Sect. page 



6. Of the Distribution and Periodicity 



of the Spots 42 



Sect. page 



Part II. Of other Stars . 

 1. Of Solitary Stars 47 



1. Introductory 1 



2. Collateral Inquiries 11 



3. Of the Outer Atmosphere of the Sun 17 



4. Of the Photosphere and the Sub- 



jacent Parts 34 



5. Of Clouds in the Outer Atmosphere 39 j 2. Of Multiple Systems 51 



Part I. — Of the Sun. 

 Section I. — Introductory. 

 1. The true surface of the sun is the outer boundary of his enormous 

 atmosphere ; but the principal escape of heat takes place from a concentric 

 layer at avast depth beneath the surface. Within this luminous film there 

 is a dark body, glimpses of which are occasionally seen as the umbrae of spots. 



2. The part of the atmosphere above the photosphere, which may be 

 conveniently called the Outer Atmosphere, is eminently transparent to 

 most of the rays which emanate from the shell of clouds, or from be- 

 neath them. But this is not the case in reference to others. The 

 atmosphere absorbs rays of those refrangibilities which correspond to the 

 dark rays visible in the solar spectrum, and multitudes of others of a like 

 kind beyond the limits of the visible spectrum. The depth of the atmo- 

 sphere is so enormous that we must conclude it to be many times more 

 than sufficient to act as an opake screen in reference to the great majority 



* Kead June 20, 1867 : see Abstract, vol. xvi. p. 25. A part of the second section of 

 the MS. sent to the Eoyal Society has been published in the Phil. Mag. for Aug. 1868 ; 

 and the substance of an Appendix suggesting observations to be made on the occasion of 

 the Solar Eclipse of Aug. 1868, winch also forms part of the MS., was published in the 

 I Monthly Notices ' of the Astronomical Society for Dec. 1867, and reprinted in the Phil. 

 Mag., vol. xxxiv. p. 502 (1867). The rest of the paper is printed here. 



VOL. XVII. B 



