6-OS. VZ- 



If^l b 



A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

 Ot Nature trusts the mind which builds for aye." — WoRDSWOR'i H. 



OPTICAL PROJECTION browning's platyscopic lens. 



^^"'"'^'^^ l~riV^OCVyl ■Vyi'M. with Larger Angles, increased Field, ar.d improved Definition 



EXPERIMENTS 



ON 



LIGHT. 



(See 

 ILLUSTRATED 



CATALOGUE, 



SIX STAMPS.) 



Set of Three Prisms, mounted as above, with Screens to show 



Principles of Achromatic Lens and Direct Vision Spectroscope 



on the Screen. 



NEWTON & CO., 3, FLEET STREET, LONDON. 



3B x:o 



NEW 



MICROSCOPE 



THE 



"BRITISH STUDENTS." 



Microscope Stand No. 55, as 

 figured, -with Iris Diaphragm, 

 One Bye-piece; Double Nose- 

 piece, Two Object-glasses, 2/3" 

 and 1/6'. adjusted to be in 

 about focus, and the v^hole 

 packed in polished Mahogany 

 Case, 



£6:8:6 



R. & J. JSECK:, Ltd, 



68 CORNHILL, LONDON, E.C. 



AN ACHROMATIC COMBINATION. 



COMBINING THE DEFINITION OF A MICROSCOPE WITH THE 

 PORTABILITY OF A POCKET LENS. 

 " If you carry a small Platyscopic Pocket Lens (which every observer of 

 Nature ought to do)." — Grant Allen in Knoivlecige. 



Tht Platyscopic Lens is invaluable to botanists, mineralogists, or enicr- 

 mologists, as it focuses about three times as far from the object as the 

 Coddington Lenses. This allows opaque objects to be examined easily. 



The Platyscopic Lens is made of four degrees of power, magnifying 

 respectively lo, 15, 20, and 30 diams. ; the lowest power, having the largest 

 field, is the best adapted for general use. 



The Lenses are set in Ebonite Cells, and mounted in Tortoiseshell Frames. 



Price of the Platyscopic Lens, moitnted in Tortoiseshell, magnifying either 



10, 15, 20, or 30 diameters, each power, 15s. 



In nickelised Gertnan Silver, each poiver, 17s. 6d. 



Illustrated Description sent free. 



JOHN BROWNING. 63 STRAND , LONDON. W .C- 



SPECTACLES 

 ELECTRIC LIGHT, INCANDESCENT GAS, 



And other Powerful Illuminants. 



NEGRETTI & ZAMBRA'S 

 THERMOSCOPIC LENSES 



ProU-Ll x\k ICv.-, from Gl.ire. .'iiul 



RENDER THE LIGHT SOFT AND COOL. 



/l/iistratcd Price Lists o/Oftkal and Mettorolo^ii-al Inslriiments 

 Free ty Post lo all /■arts of the World. 



NEGRETTI AND ZAMBRA, 

 SCIENTIFIC INSTRUMENT MAKERS to THE QUEEN, 



38 HOLBORN VIADUCT, E.C. 



BRANCHES . 45 CORNHILL; 122 REGENT STREET. 



