February, 1915. 



KNOWLEDGE. 



vu. 



WATSON'S 

 BRITISH-MADE 

 MICROSCOPES 



Special arrangements have been made 

 for prompt supplies of 



Watson's Microscopes and Accessories 



to replace those of Continental mabe that are 

 unobtainable in consequence of the War. 



NO INCREASE IN PRICES 



The 24^.'' Edition of Watson's Gataiogue 

 of Microscopes and Accessories, 



192 pages, has just been issued, and contains new 

 models, new accessories, and many improvements. 



Make Your Monocular into a Binocular 



Microscope. It can now be done by the 

 use of a WATSON'S New 



"BICOR" 



BINOCULAR 



ATTACHMENT 



(Patent applied for) 



It offers many advan- 

 tages, among which are 

 the following : — 



It is attached to a 

 Monocular Microscope 

 in the same way as a 

 Revolving Nose-piece. 



Tube length can be 

 varied and interocular 

 width adjusted to any 

 extent. 



Brilliance of image in 

 both tubes the same. 



No sacrifice of defi- 

 nition is observable. 



The above, with many 

 other important improve- 

 ments and introductions, 

 including a series of 



APOCHROMATIC 

 OBJECTIVES, 



are to be found in Wat- 

 son's newly -published 

 Catalogueof Microscopes. 

 \Posi free on application. 



"Bicor" Binocular Attachment. 

 "A'" Screw to attach to Monocular Body, 

 "B" Screw to receive Objectives. 

 *C" Screw to adjust for width of eyes. 



W. WATSON & SONS, LTD., 



Contractors to Ib./IE). Covernments, 

 313 HIGH HOLBORN, LONDON, W.C. 



Branches : 

 16 Forrest Road, Edinburgh ; 196 Great Portland Street, London, W. 



DEr6T5 : 



2 Easy Row, Birniinflham; 78 Swanston Street, .Melbourne, Australia; 



212 Notre Dame Street West, .Montreal, Canada. 



ptical Works— HIGH BARNET, HERTS. ESTABLISHED 1837. 



The BECK BINOCULAR 



BECK BINOCULAR MICROSCOPE. 



No. 1031 P.S. 



(Patent applied for) 



Not only an advance on 

 previous Binoculars, but 

 better than a iMonocuiar 

 with all powers. 



1. Resolution equal to that 



of a Monocular. 



2. Equal illumination in 



both eyes. 



3. Short tube length, mak- 



ing Microscope com- 

 pact. 



4. No special object- 



glasses or eyepieces 

 required. 



5. Standard angle of con- 



vergence. 



6. Stereoscopic vision. 



7. Binocular vision, saving 



eyestrain and giving 

 better results than 

 Monocular vision. 



8. Converted into a Mon- 



ocular by a touch. 



Full descriptive Booklet and Price List on application. 



R.&J.BEGK,L'^.'68Gornhill,London,E.G. 



DENT'S CLOCKS 



WATCHES AND CHRONOMETERS 



FOR SCIENTIFIC USE. 



Sidereal op Mean Time Clocks for 

 Observatories, £21 and up>vards< 



THREE GRAND PRIZES 

 AND ONE GOLD MEDAL 



FRANCO -BRITISH EXHIBITION. 



The only Grand Prize awarded 

 to a British Firm for Watches, 

 Clocks and Chronometers. 



The only Qrand Prize awarded 

 for Astronomical Regulators, 

 Chronographs, and 5hip's 

 Compasses. 



TRADE MARK 



61, STRAND, and 4, ROYAL EXCHANGE, LONDON. 



Telephone So. 61 City. 



ADVERTISEMENT RATES. 



Whole Page £6 6 O. 



Half Page 3 S O 



Quarter Page 1 15 oK,' 



One-Eighth Page 18 6'kj 



One Sixteenth Page O 10 OS; 



Pep Inch, Narrow Column O 7 Ol 



Half ,. „ „ O 4 0-' 



Discounts for Series of Insertions and Rates for Special Positions, when 



Vacant, on application to The Advertisement Manager, 

 Knowledge Olfice, Avenue Chambers, Bloomsbury Square, London. W.C. 



BEST 

 COCOA I 



SCHWEITZER'S 



EARTH.; 



GUARANTEED ABSOLUTELY PURE^OLUBLECOCOAONLY. 



