A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



' To the solid ground 

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



No. 255 5, Voa 102I 



THURSDAY, OCTOBER 3. 1918 



[Price.. Sixpence. 



r.il Post Office) 



[All Rights Reserved. 



Graphite-Selenium Ceils 



FOURNIER D'ALBE'S PATTERN. 



Great Stability and High Efficiency. 



With a sensitive Se surface of 5 sq. cm. and a voltage 20 the 

 additional current obtainable at various illuminations (in 

 metre-candles) is : — 



At 1 m.c. 

 At 50 „ 

 At 500 „ 



milliamp. 



For particulars and pi e Sole Agents: 



John J. Griffin & Sons, 



Makers of Physical and Electrical Apparatus, 



Kemble Street, KINGSWAY, 

 LONDON, W.C. 2 



VITREOSIL 



(Pure Fused Silica.) 



LABORATORY WARE 



Finely Glazed Crucibles, Basins, 



Capsules Beakers, 



Tubes for Carbon Estimation, 



and Heat Treatment of Metals. 



Superior to any Porcelain made. 



THE THERMAL SYNDICATE. Ltd., 



WALLSEND-ON-TYNE. 

 28 VICTORIA STREET, S.W. 1. 



ACCURATE 



AND 



RELIABLE 

 THERMOMETERS. 



Send a note of your requirements 



to any of our addresses, and we 



will offer you the best types we 



have in stock. 



NEGRETTI & ZAMBRA, 

 38 MOLBORN VIADUCT, EC. 1 



LONDON. '»» RE £fv T ST - 



mch is at 5 LeaJenhall Sired, EC. 3 



s i.(iadi;nhai.l st. 



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