rH 



\ WLLKLY ILLUSTRATED JOURNAL OF bCIENCL 



" To the solid ground 

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



NO. r6sr,'.VoL. 64] , THURSDAY, JUNE 20, 1901. [Price Sixpence; 



Registered as a Newspaper ^at the General Post Office.] 



[All Rights are Reserved. 



NEWTON & CO.'S 

 "DEMONSTRATOR'S" LANTERN, 



\ The most simple 



I and eflieient 



II Single Lantern 

 :' yet constrvicted 

 -7i for general 

 --j scientific work. 



I NEW CATALOGUE 



ij ofLanterns.Pro- 

 'j jection Appara- 

 tus and Slides, 

 Post Free, 



6 Stamps. 



FOR LIMELIGHT OR ELECTRIC. 



With Prism for Erecting, 

 and for Vertical Projection. 



Pkice £10 lOs. 



3 FLEET ST., 

 LONDON. 



T^AJR-GrSl 



DEMONSTRATION BALANCE 



FOR 



PHYSICAL 

 EXPERIMENTS. 



Specially designed lo show 

 the principles underlying llie 

 construction of the Balance. 



£9:0:0. 



FULL PARTICULAKS 

 ON APPLICATION. 



JOHN J. GRIFFIN & SONS, Ltd, 



20-26 SARDINIA ST., LINCOLN'S INN, W.C. 



ANEW 

 LENS 



5: 



.V^ 



^m\. Off^ 



KOR ALL 

 WORK. 



[n 3 .Skkies. 

 I. GENKR.\L. 



%, 



C^ II. CO.NVKKTIBLE. fff 



.^^ 111. .sncciAi. i'i;ocKSS. \^i 



This rapid, wide, medium or narrow angle lens all in one is 



suitable for all work. 



Full Catalogue free on application to Ike Manufacturers : — 



R. Sc <J. SECK;, ILitcl., 



68 CORNHILL, LONDON, E.G. 



NEGRETTI & ZAMBRAS 



IMPROVED 



SELF-RECORDING RAIN- 

 GAUGES, BAROMETERS & 

 THERMOIVIETERS, 



Giving continuous Records 



on Charts which only require 



changing weeliiy. 



Invaluable to Invalids and 



others unable to take daily 



readings. 



Illustrated Price List of Instruments free by Post to all 

 parts of the World. 



NEGRETTI & ZAMBRA, 



38 HOLBORN VIADUCT, E.G. 



Branched : 45 CORNHILL. and .:= REGKNT STREET. 

 AWARDED TWO GOLD MEDALS PARIS EXHIBITION 1900. 



i JUL 



