Astronomy 575 



THE SOLAR CORONA DISCUSSED BY SPHERICAL HAR- 

 MONICS, BY PROFESSOR FRANK H. BIGELOW 



The structure of the solar corona, as exhibited on photo- 

 graphs, consists of polar rays, four "wings" symmetrically dis- 

 posed on two axes, and extensive equatorial wings. These 

 appearances seen in the meridian section must be translated 

 into corresponding zones and sectors on the figure of revolu- 

 tion of the sun. The paper of Professor Bigelow proposes to 

 make this interpretation by the theory of spherical harmonics, 

 on the supposition that we see a phenomenon similar to that 

 of free electricity, the rays being lines of force and the coronal 

 matter being discharged from the body of the sun, or arranged 

 and controlled by these forces. The first business of the paper 

 is to put these pre-suppositions into mathematical form, and 

 to construct the theoretical lines of equipotential and of force. 



This theory once formulated, the next step is to test it by 

 the corona, and for this purpose the corona of January, 1889, 

 is chosen, as exhibited on the photographs made by the par- 

 ties of the Lick Observatory and of the Harvard College 

 Observatory. The test has been applied by the author to the 

 two photographs, and his conclusion is that the phenomena 

 displayed on the photographs are explained by the theory. 

 The paper is admittedly a provisional one. and it forms part 

 of a much wider research now in progress on the problem of 

 the transference of energy from the sun to the earth. 



This paper comprises twenty-two pages and is illustrated 

 with four diagrams, and one phototype plate. It was published 

 in quarto form in the same style as that of the " Smithsonian 

 Contributions to Knowledge," but was not included in the 

 volumes of that series. It was given to the public in 1889. 



