6 
Wratten Specialties 
for Microscopy 
Wratten “M” Filters and Wratten “M” Plates give the 
maximum amount of detail and the maximum amount 
of contrast when photographing stained specimens. 
Wratten Visual “M” Filters as their name 
implies, are for visual work with the microscope. 
35m.m. in diameter for Standard Substage Ring. 
Special Filters for Special Work. 
“ Notes on the use of Wratten 
* M 9 Filters ” 3d . post free . 
Kodak Ltd., Wratten Div., Kingsway, London, W.C. 2. 
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“KORISTKA” MODEL “A” MICROSCOPE 
Suitable for Microphotography, heavy foot, full-size stand with extra large tube 30 mm. dia- 
meter, suitable for all classes of work, inclinable to any angle with clamping lever, draw-tube 
engraved in mm., diagonal rack and pinion, coarse and improved special screw micrometer fine 
focussing to i/sooth part of a mm., quadruple triple nose-pieces, revolving and mechanical stage 
with scale and verniers, substage focussing by rack and pinion swing-out movement, rack and 
pinion oblique movement with centring of iris, Abbe condenser, N.A. 1.40 in cylindrical iris, 
quickly detachable, 50 mm. plane and concave mirrors, eye-pieces Nos. 4, 12 and 18, com- 
pensating No. 6 micrometer and No. 8 compensating positive, 3 ' apochromatic objectives, 
16, 8 and 4 mm., one oil immersion, apochromatic objective 2 mm. N.A. 1.30, complete in case. 
Magnifications 62 to 1300. List price £88 15s. £56 O O 
Guaranteed in every detail, and may be had on five days’ approval if desired. 
THE CITY SALE 81 EXCHANGE, 52 Cheapside, E.C.2 
SECOND-HAND AND NEW 
MICROSCOPES AND ACCESSORIES 
at prices to suit all users 
CLARKSON S, 338 High Holborn, LONDON, W.C.i 
Tel.: holborn 2149. (Opposite Gray’s Inn Road) 
STEVENS’S AUCTION 
ROOMS, Ltd. 
A SALE by AUCTION is held EVERY FRIDAY, at 12.30, which affords first-class 
opportunities for the disposal or purchase of Scientific and Electrical Apparatus, Micro- 
scopes and Accessories, Surveying Instruments, Photographic Cameras and 
Lenses, and Miscellaneous Property. 
Catalogues and terms for selling will be forwarded on application to STEVENS’S 
AUCTION ROOMS, Ltd., 38 King Street, Covent Garden, London, W.C. 2. 
