Vol. 25. JUNE 1888. No. 157. 



Published the First Day of every Month. — Price 2s. 6d. 



ft 



y) LONDON, EDINBURGH, and DUBLIN 



Philosophical magazine. 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloctis 'Philosophical Magazine,'' 

 Nicholson's 'Journal,' and Thomson's 'Annals of Philosophy.'' 



CONDUCTED BY 



SIR ROBERT KANE, LL.D. F.R.S. M.R.I.A. F.C.S. 

 SIE WILLIAM THOMSON, Knt. LL.D. F.R.S. &c. 



AND 



WILLIAM FRANCIS, Ph.D. F.L.S. F.R.A.S. F.C.S. 



FIFTH SERIES. 



N° 157.— JUNE 1888. 



WITH TWO PLATES. 



Illustrative of Mr. W. E. Stjmpnee's Paper on the Variation of the 

 Coefficients of Induction, and Professors W. E. Ayrton and John 

 Perry's on the Magnetic Circuit of Dynamo Machines. 



LONDON: 



PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. 



Sold by Longmans, Green, and Co.; Kent and Co. ; Simpkin, Marshall, and Co. ; 

 and Whittaker and Co. ;— and by A. and C. Black, and T. and T. Clark, Edin- 

 burgh; Smith and Son, Glasgow: — Hodges, Foster, and Co., Dublin: — Putnam, 

 New York :— Veuve J. Boyveau, Paris : — and Asher and Co., Berlin. 



