Vol. 5. APRIL 1878. No. 31. 



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



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE, 



AND 



JOURNAL OF SCIENCE. 



Being a Continuation of TillocKs 'Philosophical Magazine? 

 Nicholsons 'Journal j and Thomson's l 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. 



FIFTH SERIES. 



N° 31.— APRIL 1878. 



WITH THKEE PLATES. 



Illustrative of Professors Aybton and Pebby's Experiments on the Heat- 

 conductivity of Stone, and Sir Gr. B. Aiby's on the Correction of the 

 Compass in Iron Ships without use of a Fixed Mark. 



LONDON: 



PBINTED BY TAYLOB AND FBANCIS, BED LION COTJBT, FLEET 8TBEET, 



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

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



