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^f^3 



7 



A WEEKLY ILLUSTRATED JOURNAL OF SCIEN'CE. 



OPTICAL PROJECTION. 



EXPERIMENTS ON LIGHT. 



See ILLUSTRATED CATALOGUE. Six Stamps. 



PROGRESSIVE SCIENCE SERIES. 



NOW READY. 



VOLCANOES. 



I;V 



T. G. BONNEY, D.Sc, LL.D., F.R.S., 



Professor of Geology at University College, London. 

 Large 8vo, cloth extra, fiilly Illustrated, 6s, 



Polariscope for illustrating the va: 

 polarised light 



The last Vol. published was RIVER DEVELOP- 

 MENT, by Prof. I. C. RUSSELL. 



List of previous and forthcoming Vols, on application, free by po:t. 



NEWTON & CO., 3 FLEET STREET, 



A NEW DEPARTURE in CHEMICAL BALANCES. 



BALANCE on Polished 

 .Mahogany Base, Three 

 Levelling Screws, &c., 

 Plummet for levelling. 

 .Adjusting Screws for 

 counterpoising Beam. 

 Steel Knife Edges. 

 Will carT>- 100 grms. in 

 each pan and turn with 

 1-2 m.g. 24/- 



JOHN MURRAY, ALBEMARLE STREET. 



SPEC TAG LES 

 ELECTRIO LIGHT, INCANDESCENT GAS. 



And oilier Powerful 1 1 In rn inanls. 



BALANCE as above, with Agate Edges bound in Brass. Will carry loo 

 grms. and turn with 0.5 m.g. 29/6. 



JOHN J. GRIFFIN~& SONS, L d. 



20-26 SARDINIA STREET, LONDON, W.C 



NEGRETTI & ZAMBRA'S 

 THERMOSCOPIC LENSES 



Protect the Eyes from Gl:ire, and 



RENDER THE LIGHT SOFT AND COOL 



niuUratid Price /Jsis 0/ Optical iinj .Veleomta^ical InUrjimexl, 

 Jrcc i y Pat to ail /.arts c/ th e World. 



NEGRETTI and ZAMBRA, 

 SCIENTIFIC INSTRUMENT MAKERS to THE QUEEN, 



38 HOLBORN VIADUCT, E.G. 



BRANCHES : 45 CORNHILL ; 122 RECENT STREET. 



