Vol. 24. JULY 1887. No. 146. 



Published the First Day of every Month. 



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



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Being a Continuation of TillocK's 'Philosophical Magazine/ 

 Nicholson's 'Journal/ and Thomsons 'Annals of Philosophy,'' 



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



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fS ^s^^ P^ FIFTH SERIES. 



N« 146.-JULY 1887. 



WITH TWO PLATES. 



Illustrative of Dr. J. IS". Krtjseman's Paper on the Potential of the 

 Electric Field in the neighbourhood of a Spherical Bowl, and Dr. Gr. 

 A. Liebkts on the Production of Sparks in Air and other Oases. 



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