Seal as 
CXXXvi NATURE [NoveMBER 27, 1913 9 
THE . 
eitz “LORD BURY” 
Telescope. 
NEW SUBSTAGE CONDENSER J supptica in tarze numbers 
APLANO-ACHROMATIC. NLA. 1:33 for use by Travellers and 
Sportsmen. 
Vide *‘ Knowledge,” July and August, 1913.) 3 
pide’ apledes SY : Be Fitted with paneratie tube 
In ordinary mount ... Ex £3 10 O varying the power from 25 
Ditto, with iris diaphragm ... £4 00 to 35 diameters. 
an MILL ee ee . Size closed, 10”; Mlustrated — 
extended, 31”. Catalogue 
MICRO-OBJECTIVES. Part I. Pree. 
The Glasses of which our Objectives are made up are Will make out wild fowl at 
exclusively of a kind which long experience has shown 16 miles, will discern a The 
to be unaffected by atmospheric influences. The a ff : - “L > 
lenses are in particular not ‘iable to undergo agstaff at 22 miles, and ord Bury 
spontaneous changes. name of lightship at 
The following is a_ selection from our Catalogue of 10 miles. Telescope, 
recently improved Lenses :— a in bronzed brass, 
FLUORITE OBJECTIVES. £ s. d. POST FREB and fitted in Leather 
AJB ans ye fee) ees BR INVALD (60) 28070 on Sling Case (weight of 
t/B an Ware UE » _ 0°85 N.A. a el eed) receipt of telescope 2 lb. 3 02.). 
1/8 in. (double fluorite) o’95 N.A. 3 5 0 
afraiOe ms! bo Wed! Ll ven (OPA AS 200 Remit- £4 4 oO 
fx040.,.- ae .. 087 N.A. 310 0 tance. 
x/x2 in, oil immersion 1°32 N.A. 610 0 Ditto in bronzed light metal 
SAG ihe x.) MO. ops rege NeAe 1) SEB) sO (weight of telescope 1 Ib. 80z.). 
APOCHROMATIC OBJECTIVES. ] 
3/3 De, Sans A o'30 N.A. =e A . ; £5 15 Oo ‘ 
1/3 In rr o65 N.A : == SS 
6 in o'95 N.A 600 
ts oes ie 0°95 af 7 ap . de H. STEWARD, LTD., 
1/12 in. oil immersion 1°32. N.A. Opticians and Scientific Instrument Makers 
1/r2 in. do r'go N.A. 165 0 to the British & Foreign Goots., 
406 STRAND & 457 WEST STRAND, 
LONDON. 
Established 1852, 
18 BLOOMSBURY SQUARE, W.C. 
(A few doors from the British Museum), 
For THE “ CENTURY” 
High Resolving Power \ TELESCOPES. 
+) pees \ WITH 
3-in. Watson Conrady Object Glass, 
W. WATSON & SONS, Py i 3 Eyepieces, Stand, and Case, 
LTD., 
313HIGHHOLBORN _ fi! || £17:10:0 
LONDON. ’ m~ CATALOGUE FREE. 
HE Spencer Lens Company are the only.American manufacturers 
of Apochromatic objectives, side fine adjustments and many ‘other 
of the higher refinements of microscope construction. This in part 
accounts for their preference by the largest American Universities, 
Colleges, and careful laboratory workers generally. 
The many advantageous features of 
SPENCER MICROSCOPES 
will interest you. 
1913 Price List with specific information sent on request. 
SOLE AGENTS for Great Britain and Ireland (except London)— 
STANDLEY BELCHER & MASON, Ltd., Church Street, BIRMINGHAM 
Printed by Ricnarp Cray & Sons, LimiTep, at Brunswick Street, Stamford Street, S.E., and published by MacmILLAN AND Co., LimrrEp, at 
St. Martin's Street, London, W.C., and THe MacMittan Co.,, 66 Fifth Avenue, New York.—Tuurspay, November 27, 1913. 
