CXiv NATURE [NovVEMBER 13, I913 
[ELTZ ANEROID BAROMETERS 
NEW SUBSTAGE GONDENSLR || Gp'mounTaINs OR BALLOONS. 
APLANO-ACHROMATIC. N.A. 1°33 
(Vide “' Knowledge,” July and August, 1913.) 
In ordinary mount ... ir £3 10 O 
Ditto, with iris diaphragm ... £4 0 
Best Quality Move 
ments compensated 
Temperature. — 
MICRO-OBJECTIVES. 
The Glasses of which our Objectives are made up are 
exclusively of a kind which long experience has shown 
to be unaffected by atmospheric influences. The 
lenses are in particular not liable to undergo 
spontaneous changes. 
The following is a selection from our Catalogue of 
recently improved Lenses :— 
FLUORITE OBJECTIVES. £ s, d. 
With Altitude Scale 
reading up to 10,000 
feet and divided t 
every 50 feet. 
£3 10 0 
With Ititude Scale 
to 15,000 feet ane 
1/6 in. o’82 N.A. cn, pat Om wa of 
1fB ide Aci Atenas, NEA 20 0 | divided to 100 fee 
/8 in. (double fluorite) o’95 N.A. 3 0 
wight; eee 200 £4 4 0 
1/rrin. ... asd ae UR wae ee : 4 
r/czin. ... oil imm, ... 1°32 N.A. LY * 
DTG intents Dee ae INaRSRS As IO-AD With Altitede Saag 
‘ to 20,000 feet an 
: APOCHROMATIC OBJECTIVES. divided to I0O feet 
2/3 in. cae 0°30 ay : f i 
1/3 in F 
1/6 in N. 600 ——— £5 5 0 
1/8 in dis re, N. 610 0 P 
te in. oil imm. ... : 2 - : Illustrated Catalogue, Part II, Post Free. ’ 
1/12 in. do = A 
J. H. STEWARD, Ltd. 
18 BLOOMSBURY SQUARE, w.c. Opticians & Scientific Instrument Makers to the British & Bae Cool 
(A few doors from the British Museum). 
‘406 ’ 457 STRAND, LONDON 
ESTABLISHED 1852. 
9 have a world-wide reputation for Class and 
Laboratory Work. They are unequalled for 
rapidity, accuracy, and durability. 
British made at Barnet, Herts. Guaranteed for 5 Years. 
THE “RESEARCH” MICROSCOPE 
is of the siz>, design, and workmanship that give finest results with continuous working. Its many conveniences suit it for all classes of work with 
high or low powers, for original research or photography. It has :—Two inches of movement to the coarse adjustment for low-power work. | 
Large top plate to stage. Mechanical stage with movements of 13” horizontally and 1” vertically. Milled heads controlling move- | 
ments of the stage work on the same axis. Vertical lever, side limb fine adjustment. All working parts are slotted and sprung | 
so that the smoothness of movement which characterises WATSON MICROSCOPES may be maintained for a lifetime. 
PRICES :—Research Microscope, as figured and described, Stand only ... ar cu AD 3 as an Os £12. 0 Oo. 
Ditto with 2 Eyepieces, Objectives 2/3” and 1/6” N.A. 0.74, with x millimetre working distance, | 
new aplanatised Abbe Illuminator with Iris Diaphragm, Double Nosepiece, complete in Mahogany Case ~~ SAD 4 
WATSON'S 1/12” Oil Immersion Objective, 1'30 N.A., gives a flat field and exquisite definition ... ae ~ £25 Fs § 4 
WATSON’S MICROSCOPE CATALOGUE ALSO GIVES DETAILS of Blood Counting Apparatus, Instruments for Bacteriology, &c. 
Copies will be sent gratis on request, 
W. WATSON & SONS, Ltd. (**33!s"**), 313 High Holborn, London, W.C. 
Optical Works—HIGH BARNET, HERTS. 2 EASY ROW, BIRMINGHAM. 
16 FORREST ROAD, EDINBURGH Depots (212 NOTRE DAME STREET, MONTREAL, CANADA. 
Branches { 184 GREAT PORTLAND STREET, LONDON, w. 78 SWANSTON STREET, MELBOURNE, AUSTRALIA. 
A few of the many advantageous features of 
SPENCER MICROSCOPES 
Automatically lubricated fine adjustment bearings. 
Black lacquered body tubes avoiding reflection of light into eyes of user. 
Low compact construction (considerably lower than others) which affords greater 
ease and comfort in using. 
Low position of the fine adjustment head away from the mouth and breath of the user. 
Extra large stages with unusual distance from optical axis to base of the arm. 
Vi WN 
Spencer Microscopes represent careful attention to 
the little things which generally escape attention. 
SOLE AGENTS for Great Britain and Ireland (except London)— 
STANDLEY BELCHER & MASON, Ltd., Church Street, BIRMINGHAM 
Printed by Richarp CLay & Sons, Limirep, at Brunswick Street, Stamford Street, S.E., and published by MACMILLAN AND Co., Li 
St. Martin's Street, London, W.C., and THE MacmiLian Co., 66 Fifth Avenue, New York.—TuHurspAy, November 13, 1913. 
€ 
