MARCH 1870. No. 260 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloch's 'Philosophical Magazine,' 

 Nicholson's 'Journal,' and Thomson's 6 Annals of Philosophy.' 



CONDUCTED BY 



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

 AUGUSTUS MATTHIESSEN, Ph.D. F.R.S. F.C.S. 



AND 



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



FOURTH SERIES. 



N° 260.— MARCH 1870. 



WITH A PLATE, 



Illustrative of Mr. G. K. Winter's Paper on the determination of the size 

 of the Wire which, wound upon a Galvanometer or Electromagnet, will 

 produce the maximum magnetic effect in a Circuit of given external re- 

 sistance. 



LONDON: 



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Printers and Publishers to the University of London. 



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

 Co. ; Whittaker and Co. ; andH. Bailliere, London : — and by A. and C. Black, and 

 Thomas Clark, Edinburgh; Smith and Son, Glasgow: — Hodges and Smith, 

 Dublin : — Putnam, New York : — and Asher and Co., Berlin. 



