WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

 Ot Nature trusts the mind which builds for aye." — Wordsworth. 



No. 2557. Vol. 102I 



THURSDAY, OCTOBER 31. 1918 



[Price Ninepence. 



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[All Kichts Reserved 



Graphite-Selenium Cells 



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! milliamp. 



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