t I 



A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

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



COMPRESSED ACETYLENE 



AND 



OXY-ACETYLENE OUTFITS 



for Lantern Illumination. 

 50-% BRIGHTER THAN 

 OXY-HYDROGEN LIGHT. 



Write for full particulars to 



NEWTON <S CO. 



Opticians to H.M. the King, 



72 Wigmore Street, London, W. 



Wholesale Agr-nt; for Compressed Acetylene in 

 conformity with the Secretary of State's Regula- 

 tions for Cinematographs, &c. 



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 

 questions are lucidly and simply explained in 



" PHOTOGRAPHIC LENSES : 



A SIMPLE TREATISE." 



350 pages, 44 plates, numerous diagrams and 

 illustrations, cloth bound. 



R. & J. BECK, Ltd., £,£22»™£ 



REYNOLDS &, BR ANSON, Ltd. 



GRAND PRIX AWARD, TURIN. 



SOLE AUTHORISED MAKERS OF 



STROUD & RENDELL SCIENCE LANTERNS. 



he " University " Lan- 

 tern, with Russian iron 

 body, sliding baseboard, two 

 superior objectives, plane 

 silvered mirror "A," which 

 is moved by a knob causing 

 the rays to be reflected 

 upwards for the projection of 

 objects in a horizontal plane, 

 condensers 41 in. diam., prism 

 with silvered back which can 

 be used at " C," or as an 

 } erecting prism in mount "D," 

 lime-light burner, slide carrier. 

 Price complete in travelling 

 case, without reversible adjust- 

 able stage " B," £10 7 6 



Ditto, ditto, with " Phcenix " Arc Lamp 11 15 



Reversible adjustable stage " B" for supporting apparatus, extra 7 6 



The " College " Lantern, without adjustable stage, with 



lime-light curner complete 8 2 6 



Ditto, ditto, with " Phcenix " arc lamp ... 9 10 



Slit and prism for spectrum with support, for either lantern ... 1 7 6 



Polariser and analyser 2 



Catalogues post free. 



Optical Lanterns and Accessory Apparatus, 223 pages. 



Abridged List of Chemical Apparatus and Chemicals. 44 pages. 



u. j in 



Building 



nd Machin 



14 COMMERCIAL, STREET, LEEDS. 



Ane roid 

 Barometers 

 — in many sizes 

 — for all purposes. 

 Special patterns 

 for Surveying, 

 Mountaineering, 

 Aviation, etc. 



NEGRETTI & Z AM BRA 



Scientific Instrument Makers, 

 Holborn Viaduct, London, E.C. 

 City Branch : 45 Cornhill, E.C. 

 West End : 122 Regent St., W. 



