A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



To the solid ground 

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



No. 2279, Vol. 91] 



THURSDAY, JULY 3, 1913 



[Price Sixpence 



Newspaper at the General Post Office. 1 



(All Riehtv Reserved. 



John J. Griffin & Sons, L" 



KINGSWAY, LONDON, W.C. 



Scientif ic Instrument m akers. 



<\lk»- (C. V. Boys's Patent.) ^* S~ h. 



^y }r> Fop Studying Liquid Films. €f . 



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XTlCe ^O/- in United Kingdom, 1/- 



Including 2 Bottles of special Soap Solution and Full Instructions. 



SECOND-HAND 

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ROSS, 

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&c, 



In perfect 

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STANDARD 

 ANEROID 

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brass case, 4A" dial 

 divided to "01 inch 

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 witli index hand. 

 In morocco case. 

 Price £5.5.0. 

 N.P.L. certificate 

 8s. 6d. extra. 



NEGRETTI & ZAMBRA 



Scientific Instrument Makers, 

 Holborn Viaduct, London, E.C.3 

 City Branch : 45 Cornhill. E.C. 

 West End : 122 Regent St., W. 



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