
































A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE, - 
“* To the solid ground 
Of Nature trusts the mind which builds for aye.””—WOoRDSWORTH. 
No. 2789, VOL. 111] SATURDAY, ‘ABRIL 14, 1923 [PRICE ONE SHILLING 
Registered as a Newspaper at the General Post Office.] [All Rights Reserved. 
REYNOLDS & BRANSON, Lro. 
Chemical and Physical Apparatus Makers to His Majesty's 
Government (Home and Overseas Dominions), 
Laboratory Outfitters, &c. 
Gold Medals at Allahabad and London. Grand Prix and Gold Medal 
at the International Exhibition, Turin. 









APPARATUS for MACKENZIE 
and FORSTER’S THEORETICAL 
and PRACTICAL MECHANICS and 
PHYSICS as adopted by H.M. 
Government and many important 
Educational Authorities, Price Lists 
on application. 






A Vive :—‘* Theoretical and 
y 4 Practical Mechanics and Phy- 
sics,” by A. H. MACKENZIE, 
M.A., B.Sc., and A. ForsrTEr, 
- B.Sc. 
Re E . B EC 4 R & Cc = Wireless Apparatus and Accessories supplied. 
W. & J.GEORGE (LONDON) L"? PROPRIETORS CATALOGUES POST FREE. 
17 to 29 HATTON WALL, LONDON.E.C.| Optical Lanterns and Lantern Slides; Chemical and Physical Apparatus 
and Chemicals ; Chemicals of Guaranteed Purity, including ‘‘A.R." Quality. 
144 COMMERCIAL STREET, LEEDS. 

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LONDON. 
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to British and Foreign 
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Particulars and Prices on application to— 
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Kemble Street, Kingsway, 
London, W.C.2. 

