KNOWLEDGE. 



October, 1910. 



A REVOLUTION IN 

 HIGH SPEED SHUTTER WORK. 



(( 



MULTI-SPEED 

 SHUTTER. 



NEW 

 PATENT 



ARRESTS 

 MOTION. 



Instantaneous f^/ 

 Exposures 

 without 

 Sun light. 



NO HORIZONTAL 

 DISTORTION 



.^"^ 



EXTRA RAPID 

 INSTANTANEOUS 

 EXPOSURES 



o^ &r>5 lOOQ 



i "® I* \ of Second. 



SLOWER 



(r.nlli \ Tun.-) 



EXPOSURES 



With Ross' "HOMOGENTRIC" Lens the MULTI-SPEED 



forms the Best ami must KeliaMe Conil)inatiiiii for All I'luposcs. 



TELEPHOTOGRAPHY. Ross' HOMOCENTRICS 



.ul- [>ailiculaiiy adapted Um use a^ i 'i .sii i\ c^. 



Ross' Telenngatives arc specially constt-ucitii for use in conjunction 

 with these remarkable Lenses. 



"MODERN TELEPHOTOGRAPHY." a Practical ^ran^^-ll. tiy C.ipian 

 Owen Whellhr. P.iper ri-i\i_-rs. ] /ri : lif\fllr.l lio.iiHs. -j d 



ROSS Ltd., 3, North Side, CLAPHAM COMMON, S.W. 



Beck's "LONDON " Microscope 



SMALL MODEL. 



With spiral focussirii^ and swinging sulj!?tay 

 Packed in Mahogany case. 



jC s .1. jT s. 

 No. ii2C)K Stand, in case 400 

 No. 364A 2 Eyepieces . u 10 o 

 „ 912A Abbe Conden- 

 ser. o 16 o 



,, 802 5 inch(i6inm.) 



Object Glass o 12 o 

 „ S04 J; inch (4 mm.) . 

 do. or I 



., 804A i inch (3 mm.) j' ^ ^^ ° 



^ do. } 



., 3g2A Double Noae- 



piece o g 



No. 



No. 1 129. 



qN stand, in ca--e 

 No. 3fS4A 2 Eyepieces . . 

 ., Q12A Abbe Conden- 

 ser 



,, S02 5inch(i6mm.) 

 Object Glass 

 ^ inch (4inm.) 



do. 



j'o inch (2mm.)'] 

 Oil Immer- 

 lion do or 

 .1 inch (rS 

 inm.)0il Im- | 

 mersion do. . . 

 IQ2A Dubt-tight Tri- 

 ple N ose - 

 piece ....,,. 



7 11 



o 10 o 



So 4 

 Sio 



SlOA 



11 19 6 



.\ ^-inch Object Glass with 110° angle instead of 90° can be supplied 

 at the same cost, and a J-inch Ghject^Glass with 32' angle instead uf 

 17" at an extra cost of 3/- 



Full 

 Particulars of 



R. & J. BECK, Ltd., 



68, CORNHILL, LONDON, E.G. 



CANTOK LbCTLKKS on the THEORY OF THE MICROSCOPE, 

 by Conrad Beck. Price 1/-. 



F. WIGGINS & SONS, 



102, 103, 104, Minones, LONDON, E 

 Contractors to H. M 

 Oovernment 



FOR 



LAMPS' 



STOVES, 



VENTILATORS, 



ELECTRICAL WORK 



Af^D ALL PURPOSES. 



Largest Stock in the World. Tel. No. 2248 Avenue. 



THE MARl.INO ENDOWED iiCHOOE, 

 5troud (Qlo.s. 1. 

 \ I'ui-li. Kn. I, ,uol -.,!;, ,ol (iS;ul. Mathe- 

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 strong feature. 1 Kcccni smcssii i}uni,if 



3 Fust Classt-s Tripos, :i7 London MatHc, 17 

 /litet: Sci.,rUJ. Splendid modern Buildings on 

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BOOKS! 



Pooks on Scienlific, Technical, 

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SECOND HAND AT HALF PRICES! 

 New, at 25 Discount. 



Catalogues pRtt:. 



State wa 

 approval. 



Pooks sent on 



BOOK'S BOUGHT— BEST PRICES GIVEN. 



W. & G. FOYLE, 135. Charing Cross Road, 

 London, VV'.C. 



BIOLOGICAL MATERIAL. 



Living and Preserved 

 Specimens for Class Work and Researcti. 



LIST FREE. 



L, HAIG, 9, Little James Street, Gray's Inn Road, London, W,C, 



We have on hand a few Sets of the series of 



Star Maps which have appeared from time to 



time in "Knowledge." 



These form a COMPLETE 



STAR ATLAS 



comprising Twelve Maps of the Heavens and 

 Two Index Maps. 



Price 2/6 Net, 



Per Set. 



Also, some Sets of the 12 Photographs of 



THE MOON 



which may be mounted together, or bound 

 as an Atlas. 



Price 2/6 Net, 



Per Set. 



"KNOWLEDGE" OFFICE-42, BLOOMSBURY SQUARE, LONDON, W.C. 



/-"^ 



