A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. \ '•/;■; 



u To the solid ground 

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



No. 2555, Vol i< >j] 



■ 1 1 Post Office ] 



THURSDAY, OCTOBER 17, 1918 



(Price Sixpence. 



[All Rights Reserved. 



Graphite-Selenium Cells 



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 : — 



Kor particular- and prices apply to the SOLE AGBNTS : 



John J. Griffin & Sons, 



Makers of Physical and Electrical Apparatus, 



Kemble Street, KINGSWAY, 



LONDON, W.C. 2 



CHEMICALS 



Analytical, Technical and Research. 



RE 7™ APPAR ATUS 



' L ;_. = Balances 



>£Hr BENCHES 



Fume Chambers, etc., 



for 



a snow crystal Chemical Laboratories 



%6 % 

 m CRYS 

 Price Lists and Estimates on Application. 



REYNOLDS & BRANSON, LTD., 



Contractors to the War Office, Admiralty, and 

 Egyptian Government, &c. , 



14 COMMERCIAL STREET, LEEDS. 



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 HOLBORN VIADUCT, E.C. i 



5 LEAD b : ?'c H 3 LL ST ' LONDON. 



ST Our City Branch is at 5 UaJcnhall Street. E.C. 3 



