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A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 
“To the solid ground 
Of Nature trusts the mind which builds for aye."—WorRpswortTh. 
No. 2468, VoL. 98] 
THURSDAY, FEBRUARY 15, 1917 
[| PRICE SIXPENCE. 
Registered as a Newspaper at the General Post Office.] 
[All Rights Reserved. 
X-RAY TUBES 
Of all descriptions Made, 
Repaired, & Re-exhausted 
on the Premises. 
Coolidge Tubes kept in stock. 
NEWTON & WRIGHT, Ltd. 
72 WIGMORE STREET, W. 
Sole Agents for Macalaster Wiggin X-Ray Tubes, 
Undoubtedly the Finest Tubes 
in the World for all purposes, 
DUROGLASS L™: 
14 CROSS STREET, HATTON GARDEN, E.C. 
Manufacturers of 
Borosilicate Resistance Glassware. 
Beakers. Flasks, Ete. 
Soft Soda Tubing for Lamp Work. 
General Chemical and 
Scientific Glassware. 
Special Glass Apparatus Made to Order. 
DUROGLASS WORKS, WALTHAMSTOW. 
AGENTS: 
BAIRD & TATLOCK (LONDON) LTD. 
14 CROSS ST., HATTON GARDEN, E.C. 
REYNOLDS & BRANSON, Ltd., 
Chemical and Scientific Instrument Makers to His Majesty’s*. 
Government (Home & Overseas Dominions), Laboratory Furnishers 
and Manufacturing Chemists. 
CHEMICAL, PHYSICAL, and TECHNICAL LABORATORIES 
Fully Furnished with BENCHES, FUME CHAMBERS, &c. 
INSTITUTIONS EQUIPPED INCLUDE :— 
The National Shell Filling Factory, Leeds, and various Munition Works ; 
Che National Physical Laboratory, Teddington ; Laboratories at Messrs. 
Brunner, Mond & Co., Ltd., Northwich; Messrs. Meadowcroft & Son, Ltd., 
Blackburn; The Shelton Iron, Steel and Ceal Co. ; Science Laboratories 
at the Grammar School, Dunstable; Imperial Service College, Windsor ; 
Batley Grammar School; Transvaal Dept. of Agriculture (txperimental 
Farm), Potchefstroom ; The Technical Schools, Morley and Yeadon; The 
Girls’ High Schools at Barnsley, Beverley, Doncaster, Leeds, Harrogate, 
Nuneaton, Sherborne, and York; Radley College, Uxford; The Schools, 
Shrewsbury ; St. Mary's College, Winchester ; and many others. 
Catalogue of Chemical and Physical Apparatus and Chemicals post free. 
Designs of Benches and Fittings to suit all requirements. 
14 COMMERCIAL STREET, LEEDS. 
A New Barograph—tTHE ‘‘ JORDAN.” 
(Regd. Design ¢ 2871.) 
Shows at a glance the movements of the barometer during 
the preceding days. 
Descriptive Leaflet post free on application to 
NEGRETTI & ZAMBRA, 
38 HOLBORN VIADUCT, E.C.; 
45 CORNBILL, E.C.; 122 REGENT ST., W. 
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