506 F. H. Bigelow — The Theory of the Solar Corona. 



from the equation of the force at any point, F ~~r 



R 



(3 cos 2 w-f 1)^5 is n °t what he intended to have appear. Instead 

 of reading, N"=— ^— (3 cos 2 a> + l)' (1 — cos w) +^E 2 sin 2 o;, it 



should read, N=— — — sin 2 w + ;r^Ra; 2 sin 2 w. The equation in 



XV 



, i p • i r« „sill 2 Gj9 _ . , 



its corrected form gives two terms, the first, 2n(pa ----- , which 



t\i 



is identical with that employed by me in my paper, and the 



second, 7r^R 2 sin 2 &> which Mr. Nipher ascribes to the action of 



a uniform field of force surrounding the Sun. 



2. At this place the ways part, and the irrelevant criticism 

 begins. The equation in .N with one term represents a certain 

 condition of things; the equation in N" with two terms is a 

 different case and belongs to another state of things. If any- 

 one is curious to see the two cases fully represented graphically, 

 let him turn to Maxwell's Electricity and Magnetism, vol. i, 

 fig. 5, Art, 143, for the first, and to vol. ii, fig. 15, Art. 434, 

 for the second. Professor Cipher is at liberty to ascribe the 

 second case, as his own, to the conditions about the sun, but 

 there is no need to dedicate it to my theory, because it was 

 not employed by me. There is no evidence that the sun is 

 placed within a field of uniform force, produced outside of 

 itself, nor is it necessary to resort to such a supposition in 

 order to account for the forms of the coronal streamers, as seen 

 from the earth. 



When we come to consider the earth the case is different 

 from that of the sun, since we have some reasons for thinking 

 that the earth lies in a uniform held, generated by the action 

 of the sun upon the earth. As I pointed out in the same paper 

 it may be necessary to treat the field surrounding the earth by 

 the full equation, written by Professor ISTipher. I have pub- 

 lished a theory for doin^ so. employing the configuration of 

 the auroral streamers, if suitable observations can be obtained; 

 [this Journal, February, 1891.] 



3. It must be perfectly understood by students of this sub- 

 ject that most of the mathematical devices for discussing the 

 field of force surrounding a polarized sphere, are physical 

 fictions. There are many such devices, as for instance : (1) two 

 equal masses of electricity with opposite signs placed infinitely 

 near together at the center of the sphere, (2) the cosine distri- 

 bution from a maximum superficial density at the axis, (3) the 

 polarized sphere or the layers of gliding, (4) an indefinitely 

 small magnet at the center of the sphere, and others. From 

 such suppositions the mathematical treatment builds up the 



