A WEEKLY ILLUSTRATED JOURNAL OF SCIENC 



■" To the solid ground 

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



MINIATURE ARC LAMP. 



Will work from any ordinary house lighting circuit. 

 Complete with resistance and OQ Q fl 



mechanical tray ... *« O U 



(For alternating current 10 6 extra.) 



'on of An Lamfs and Resistances now ready, 

 post free on request. 



NEWTON &, CO. (late of 3 Fleet Street), 



Opticians by Royal Warrant to H.M. the King. 

 72 WIGIWORE STREET, 'W. 



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 swine; back, the 

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

 questions are lucidly and simply explained in 



" PHOTOGRAPHIC LENSES : 



A SIMPLE TREATISE." 



35° pages. 44 plates, numerous diagrams and 

 illustrations, cloth bound. 



R. & J. BECK, Ltd., ™ ™l™l 



LL, 

 B.C. 



REYNOLDS & BRANSON, Ltd., 



Manufacturers of Chemical and 

 Physical Apparatus. 



GRAND PRIX AWARD. TURIN, 1911. 



THE "RYSTOS" ELECTROSCOPE. 



This Electroscope, with paraffin 

 insulator, remains charged for at least 

 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. 



(a) Price with attachment for two Wires and top re-\ 



movable for cleaning the glasses.. / 



(6) Ditto, with two glass tubes for showing the leak- | 



age caused by a radio-active gas.. 

 c) Ditto, with transparent scale, lecturer's pattern, 't 



of i 

 i lanter 



age of gold leaf and : 



5/- each. 



j- S/6 each. 



■7/6 each. 



14 COMMERCIAL STREET, LEEDS. 



ANEMOMETER 



recording the 

 PRESSURE and 

 the DIRECTION 

 upon one chart. 



Write for 



^Particulars 



of the Anemo- 



Biagraph and 



Direction Recorder. 



NEGRETTI&ZAMBRA, 



38 Holborn Viaduct. E.C. ; 



45 Cornhill. E.C. ; 



122 Regent Street, W., 



London. 



