November, 1910. 



KNOWLi:n(^,i: 



AITCHISON & Co. 



Opticians to H.M. Government. 

 The only makers in the world who have 

 succeeded in making 

 Prism Binoculars magni- 

 fying 25 diameters. 



PRICE £12 10 O 



with best solid leather case. 

 W'itii central focussing motion £1 extra. 



Every Glass Tested at the 

 BRITISH GOVERNMENT 

 LABORATORY AT KEW, 

 and Certificate of Power, Defi- 

 nition, &c., signed by Dr. 

 R. T. Glazebrook, F.R.S., 

 the director, is given with the 

 Glass to Purchaser. 



The Night and Day Marine Wide Aperture Prism Glasses. 



X 9 MAGNIFICATION £6 10 x 16 MAGNIFICATION £8 10 



X 12 MAGNIFICATION £7 10 x 20 MAGNIFICATION £10 10 



X 25 MAGNIFICATION £12 10 



With ijenl:al iV.t u--i;i.; m >ll n £1 exlr.i. 



Prices include Best Solid Leather ^silng Case, postage an packing to .'my 



part of the World. 



/'?-/<(■ Lisf o^ Ptisi't a)td other Binontttus l^o'^f F'it\ 



AITCHISON & Co. 



Opticians to H.M. S: L.S.A. floifs.. 



428, STRAND, and Branches, LONDON. J 



bSIb 



TRADE MARK 



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tjvering the subjects .f Astronomy, Bio!og:y, Botany, Chemistry, 



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Philosophy . Physics, Physiology, Sociology, Technology. Travels, 



Zoology. iScc. in aJuition to Every Branch of Medical Science. 



A'eu' 



[Corner oi Library Readiny Knom. 



Works aad Sew Editions are added to tiie Library 

 immediately on publication. 



Subscription. Town or Country, from 21s. 



The Library Reading Room i- j -n daily for the use of .Siih>ci ibti,-.. 



I London: H. K. LEWIS, 136, Gower Street, W.C. 



^^ BOOKS IN ALL DEPARTMENTS OF LITERATURE. 



mm^mm^ 



THOTOMICROGRAPHY' 



Containing a discussion of ihe considerations L^overn- 



ing the Contrast obtained in the Photography 



of Microscopic Specimens. 



Free oil application, enclosing Id. stamp 



for fxistagc. to 



H^ WRATTEN & WAINWRIGHT, Ltd., CROYDON. 



I 





'*i 



SECOND-HAND PERT. 



j NoiAT Ready j 



i CATALOGUE OF SECOND-HAND SCIENTIFIC " 

 INSTRUMENTS, CHIEFLY IVIICROSCOPICAL 



NATURE says: — ''Workers in science will find 

 a good selection of instruTnciit,s likclj' to proviiie 

 the .ipparatus of which they may be in search."' 



I 



Post free on application. 

 H. F. ANGUS & Co.. 83. Wifimore St.. LONDON. W. ■ 



BAUSCH & LOMB'S 



CELEBRATED 

 MICROSCOPES. 



Nevy and Improved Models. 



B H 8 LABORATORY MODEL (.s rigui^dj 



with §-in., ?.-in., and ■j'^-in. (oil immersion) objectives, 

 2 eye-pieces, screw-out substage. w ith Alihe con- 

 denser, and triple dust-proof noscpiece. in calnnet. 



£13 2 6 



B B H .S L.M<GER LABORA- 

 TORY IV10DEL, as al.ove, hu: 



u nil S(.ieu-ijut iiilt^ su ins-down 



.ubsia-e £18 4 6 



B H 4 iVVODEL, with ^-in. and 

 |-in. objectives. 2 ej-epieces, and 

 circular dust-proof nosepiece. 



£5 12 6 



Microtomes, Centrifuges, 

 Photo - micrographic and 

 Projection Apparatus, 

 Precision Laboratory' 

 Glassware, &c. 



Inspection cordially invited at our 

 Show-Rooms or Lists sent )iost fr-^e. 



^% THE BAUSCH & LOMB OPTICAL Co., 



Conii-nctors to British and foreign Goi'ernfnfiits. 



19, THAVIES INN, HOLBORN CIRCUS, 

 IV Mm LONDON, E.G. 



k 



