A WEEKLY ILLUSTRxVTED JOURNAL OF SCIENCE. 



" To the solid ground 

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



Wheatstone's Compound Gyroscope 



PACKED IN CABINET CASE. 



--. of Gyroscopes 

 tu be had p.D^t free from 



NEWTON 6 CO., Opticians to H.IVl. King Ceorge V. 

 72 WIGMORE STREET. LONDON. W. 



REYNOLDS & BRANSON, Ltd., 



Manufacturers of Chemical and Physical Apparatus. 



GOLD MEDALS: LONDON. 190B. ALLAHABAD. 1911. 



GRAND PRIX. TURIN. 1911. 



MEDALS, YORK, 1912. 



THE "RYSTOS" ELECTROSCOPE. 



This Electroscope, with paraffin 

 insulator, remains charged for about 

 a day, and has been used with the 

 greatest satisfaction in many secondary 

 schools for the last ten years. A 

 customer states that the batch of two 

 dozen, obtained two years previously, 

 has remained in efficient condition 

 during that time. 



s and top re-1 



(a) Pr 



with attac^ 



vable for cl 



(6) Ditto, with two g 



age caused by 



(c) Ditto, with transi 



nent for two 

 aning the gl 

 iss tubes for showing the lealt- 



I radio-active gas.. 



irent scale, lecturer's pattern 



STUDY 

 THE LENS 



It is the Key to Success in Photography. 



Who can expect to excel who does not understand 

 how to use the diaphragm, the swing back, the 

 rising front, focussing scale, &c., &c. ? All such 

 (juestions are lucidly and simply explained in 



" PHOTOGRAPHIC LENSES : 



A SIMPLE TREATISE." 



350 pages, 44 i>lates, numerous diagrams and 

 illustrations, cloth bound. 



R. & J. BECK, Ltd., lf„S°^S!^4^^: 



5/- each. 



I S/6 each. 



age of gold leaf and scale \ lie each. 



14 co]vi]vie:xcci.h.e.. stkeejt, z^je:e:x>s. 



The 



"Public School" 

 Set of 



Meteorological 

 Instruments 



forms 



a simple complete Climatological 

 Station at a moderate price. 



A Pamphlet describing this Set. and Price 



List, "Meteorological Irtslrurrtenls," will 



be sent post free to ariy address. 



NEGRETTI & ZAMBRA 



Holborn Viaduct, London, E.C. ; 

 45 Comhill, E.G.; and 122 Regent Street, W. 



