Vol. 



55. ' June 1890. 



rublished the Last Day of every Month, 

 , [PRICE 2s. 6d.] 



THE 



PHILOSOPHICAL MAGAZINE 

 AND JOURNAL: 



COMPREHENDING 



THE VARIOUS BRANCHES OF SCIENCE, 



THE LIBERAL AND FINE ARTS, 



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AGRICULTURE, 



MANUFACTURES AND COMMERCE. 



NUMBER CCLXVI. 

 For JUNE 1820. 



WITH A PLATE BY PORTER 

 Illnstrative of Capt. Forman's Essay on the Refl'^aion, Refrac-i 

 lion and Inflection of Light, &c, ; and Mr. Chas. Bonny- 

 castle's Communicacion i.especting the Influence of Masses 

 of Iron on the Mariner's Compass. 



BY ALEXANDER TILLOCH, 



I.R.I.A. M.G.S. M.R.A.S. MUNICH, F.S.A. EDIN. ANDPEllTH, &C. 



LONDON: 



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 man, Gl;tsg(>\v: and Gilkert and Hodges, Dublin. 



