Vol. 45. JUNE 1873. No. 302. 



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



THE 

 LONDON, EDINBURGH, ato DUBLIN 



-r * 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of Tilloch's ( Philosophical Magazine' 

 Nicholson's e Journal , and Thomson's { Annals of Philosophy ' 



CONDUCTED BY 



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

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



AND 



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



FOURTH SERIES* 



N° 302.— JUNE 1873. 



WITH TWO PLATES, 



Illustrative of Mr. O. Heaviside's Paper on Duplex Telegraphy, and 

 Mr. H. Wilde's on some Improvements in Electromagnetic Induc- 

 tion Machines. 



LONDON: 



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Printers and Publishers to the University of London. 



Sold by Longmans, Green, Reader and Dyer ; Kent and Co. ; Sinipkin, Marshall and 

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



