761.9.. MARCH 1880. No. 55. 



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THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE. 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of TillocKs 'Philosophical Magazine] 

 Nicholsons 'Journal] and Thomsons 'Annals of Philosophy.'' 



CONDUCTED BY 



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

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



AND 



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



FIFTH SERIES. 



N° 55.— MARCH 1880. 



> 

 >- 



WITH TWO PLATES. 

 Illustrative of Mr. L. Fletcher's Crystallography Notes, and Mr. J. 

 Bridge's Paper on a Calculating Apparatus. 



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