"! insf* 



A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

 liure trust.'; the mind which builds for aye." — Wordsworth. 



No. 2569, Vol. 102] 



THURSDAY, JANUARY 23, 1919 



[Price Ninepence. 



Registered as a Newspaper at the General Post Office] 



(All Rights R eserved. 



BALANCES & WEIGHTS 



firaphite-Selenium Cells 



FOURNIER CfALBE'S PATTERN. 



Great Stability and High Efficiency. 



With a sensitive Se snrface 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 SOO „ 



} milliamp. 



1 



2 



For particulars and prices apply to the Sole Agents : 



John J. Griffin & Sons, 



Makers of Physical and Electrical Apparatus, 



Kemble Street, KINGSWAV, 

 LONDON, W.C. 2 



REYNOLDS & BRANSON, Ltd. 



Chemical Glassware, Chemical and Physical Apparatus 



Makers to His Majesty's Government (Home and Overseas 



Dominions). Laboratory Outfitters, &c. 



STROUD & RENDELL SCIENCE LANTERN. 



The "University" Lan- 

 tern, with Russian iron 

 body, sliding baseboard, two 

 superior objectives, with rack 

 and pinion for focussing, con- 

 densers 4 1 in. diara., plane 

 silvered mirror " A," which is 

 moved by a knob causing the 

 rays to be reflected upwards 

 fur the projection of objects 

 in a horizontal plane, silvered 

 prism which can be used at 



in mount " D," limelight 



burner, slide carrier. Price 



complete in travelling case, 



...£15 



for supporting apparatus, 

 CATALOGUES (Post free). 



Lanterns and Accessory Apparatus, 

 amical Apparatus and Chemicals. 



17 5 



14 COMMERCIAL STREET, LEEDS. 



BECKMANN THERMOMETERS 



With 6 degrees Centigrade divided 

 into 001° C, are now made 

 throughout at our own works. 



NEGRETTI & ZAMBRA 



38 HOLBORN VIADUCT, EX. i 

 5 LEADENHALL ST., E.C. 3 

 122 REUENT STREET, W. 1 



LONDON. 



