March, 1915. 



KNOWLEDGE. 



WATSON'S 

 MICROSCOPES 



The best obtainable. British-made throughout. 

 rppirjjr'J^T' . Enable the [worker to gel the best out o( his 



CONVENIENT '. Every necessary movement Is embodied. 



STABLE * With either tripod or horseshoe loot. 



PRACTICAL : intended »or hard work. 



LAST A LIFETIME. 



The "RESEARCH" Microscope. 



Specification : — 



Mechanical Stage — Giving move- 

 ments 2" X 1|". Botli milled 

 iieads on same axis. 



Fine Adjustment — Side limb, 

 vertical lever type. 



Coarse Adjustment — Diagonal 

 rack, long range, enables 

 3" objecti\>e to be focussed when 

 on nosepiece. 



Compound Substage — Rack and 

 pinion focussing with centering 

 screws for condenser. 



Movements are slotted and sprung 

 throughout, and wear can be at 

 once compensated. 



Tripod foot giving stability in 

 any position. 



Guaranteed for 5 years. 



Fop the Ainateup op Ppofessional this 

 instrument embodies every desirable movement, and 

 is at once the cheapest and the best 

 obtainable. 



Prices: — , 



Research Microscope 



do. do. with eyepieces 



No. 2 and No. 4, objectives 1" and 

 i" (1 mm. working distance for pond 

 life or blood counts), aplanatised 

 Abbe illuminator with iris diaphragm. 

 In mahogany case 



Full details of the above, and also of 32 Different 

 Models at all prices, will be found in Watson's Micro- 

 scope Catalogue, No, 2k, which will be forwarded 

 gratis on application. 



£12 10 



17 17 6 



APPARATUS 



PHOTO-MICROGRAPHY. 

 METALLURGY. 

 BACTERIOLOGY. 



FOR:— 



POND LIFE. 

 PETROLOGY. 

 PROJECTION. 



H.fflMATOLOGY, &c,, &c. 



W. WATSON & SONS, LTD., 



Contractors to 1b.^. governments, 

 313 HIGH HOLBORN, LONDON, W.C. 



Branches : 



16 Forrest Road, Edinburgh; 196 Great Portland Stre»t, London, W. 



Dei6ts : 



2 Easy Row, BirminfSham; 78 Swanston Street, Melbourne, Australia; 



212 Notre Dame Street West, Montreal, Canada. 



Optical Works— HIGH BARNET, HERTS. ESTABLISHED 1837. 



THElONDON'MIGROSGOPE 



("REGENT " 



Model). 



This instrument is somewhat 

 .similar, though larger, than the 

 Large "" London" Model. The 

 slow motion is about four times 

 as fine, working in the most per- 

 fect manner by means of micro- 

 meter screw and a .system of 

 levers. The limb is provided 

 with a handle for lifting. Still 

 more room is allowed for the 

 rack and pinion, centring and 

 substage. The substage swings 

 out laterally. An iris diaphragm 

 is set in the thickness of the 

 stage, and remains in position 

 when the substage is swung out. 



Stand, in Case, with Mechanical Stage 



'A Eyepieces 



I in. (14 mm.) Object Glass, 32° .. 



I in. {4 mm.) Object Glass, 110" . . 



^ij in. (2 mm.) Oil Immersion, 1*3 n.a 



Beclc Achromatic Condenser, 1" N.A. 



Dust-tight Triple Nosepiece .. 



13 10 

 15 



15 



1 10 

 5 

 3 

 17 



£25 7 6 



Particulars Of Ra Ob U* BcCKj LtD., 

 68, Co rnhill, LONDO N, E.G. 



CANTOR LECTURES on the THEORY OF THE MICROSCOPE, 

 by Conrad Beck, Price 1/-. 



DENT'S CLOCKS 



WATCHES AND CHRONOMETERS 



FOR 5CIENTtFIC USE. 



Sidereal or Mean Tiine Clocks for 

 Observatories, £21 and upwards. 



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 Grand Prize awarded 

 for Astronomical Rej^ulators, 

 Chronographs, and Ship's 



Compasses. 



TRADE MARK 



CAUTION. 



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



Telephone So. 61 City. 



The Proprietors of SCHWEITZER'S 

 " COCOATINA, " " FAIRY COCOA, " &c., 



beg to inform their clients that NONE of their 

 products are manufactured in Germany ; that 

 they are a private ENGLISH COMPANY man- 

 aged by a Board of ENGLISH DIRECTORS; and 

 that all shares are held by relatives and con- 

 nections by marriage of the late sole proprietor^ 

 Captain Thomas Edward Symons, R.N. 



— JOHN KING, •■ KlTowiedgl." — 



UXBRIDGE, SOUTHALL, AND EALING, 



is favourably equipped for the 



PRINTING OF SCIENTIFIC BOOKS, BROCHURES, &c., 



and will be pleased to submit Estimates. 



Address all Communications to 213, UxUrldge Road, Ealing, London, W. 



TELIPMONSi 1144 EaLINS. 



