.1 Xote on Magnetic Storms. 665 



values of 6 up to about 150° C. is probably connected with 

 tin 4 results contained in Table IV., columns 2, 7, and 8. It 

 will be noticed in column 2 that the ratio of the resistances 

 of the two anemometer wires corresponding to the maximum 

 deflexion continuously increases as the heating current 

 is diminished, and moreover, while for large values of the 

 heating current the temperature of the second wire, corre- 

 sponding to the maximum detlexion, is considerably less than 

 that corresponding to zero flow, for small values of the heating- 

 current, the temperature of the second wire corresponding 

 to the maximum deflexion is greater than that corresponding 

 to zero flow. 



The research detailed herein was carried out in the 

 Physical Laboratory of the South Metropolitan (las ( Jompany. 

 Mr. W. H. B. Hall assisted in the experimental portion of 

 the work. 



The author desires to express his sincerest thanks to 

 Dr. C'liarles Carpenter, C.B.li!., for his unfailing readiness 

 to provide all facilities for carrying out the work. 



Physical Laboratory, 



South Metropolitan Gas Company, 

 709 Old Kent Road, S.E. 15. 

 16th August, 1920. 



LXXV. A Note on Magnetic Storms. By S. Chapman, M.A. t 

 JD.Sc.j P.R.S., Professor of Mathematics and Natural 

 Philosophy in the University of Manchester* . 



1 . T N the Phil. Mag. for Dec. 1919, Prof. F. A. Lindemann 



JL published a paper on magnetic storms, in which 

 certain criticisms were made of a theory of my own f, and 

 an alternative form of part of that theory was proposed. 

 I have been unavoidably delayed in answering those cri- 

 ticisms, and the following notes will only indicate the 

 general nature of my reply and some further conclusions, 

 which I hope to support and extend by detailed calculations 

 on a later occasion. 



2. Prof. Lindemann criticises my theory because it pos- 

 tulates a stream of corpuscles " mainly or entirely of one 

 sign of charge " J projected from the sun and penetrating 

 into the earth's atmosphere : he shows, on the basis of certain 



* Communicated by the Author. 



+ <; An Outline of a Theory of Magnetic Storms," Proc. Hoy. Soc. A, 

 xcv. (1918). 

 % Ibid. p. 78. 



Phil. Mag. S. 6. Vol. 40. No. 239. Nov. 1920. 2 X 



