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A WEEKLY ILLUSTRATED JOURNAL OF SCIEN@E. 
““To the solid ground 
Of Nature trusts the mind which builds for a ”__WORDS WORTH. 
No. 2301, VOL. 92] THURSDAY, DECEMBER Ft 7 ioe [PRICE SIXPENCE 
Registered as a Newspaper at the General Post Office. } 
{All Rights Reserved. 
BUY DIRECT FROM 
FE E.BECKER &CO,HATION WALL, 
(W.&J.GEORGE. LTD.,SUCC#=) LONDON, EG: 
JOHN J. GRIFFIN & SONS, L” 
Kemble St., KINGSWAY, LONDON, W.C. 
re aoe 
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A NEW CHEAP FORM. 
Price 2/G Postage 4d. Extra Bottles of Solution, 6d. 
Leitz 
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 ot 
recently improved Lenses :— 
FLUORITE las ates Se sete 
1/6 in. 1 = 2 N.A. 200 
1/8 in. rs N.A. 2 0.0 
1/8 in. (double fluorite) o'g5 N.A. 3 Bae 
1froin. ... # oa 87 N.A. 200 
x/ix 18. ... == .. 0'87 N.A. 310 0 
1/12 in. oil immersion 1°32 N.A. 610 0 
1/x6in. ... do. con ge) Ne As 710 0 
APOCHROMATIC OBJECTIVES. 
2/3 in... om o'30 N.A. 300 
x/3 ins... = «. o'65 N.A. 400 
1/6 in. ... = w O95 NIA. 600 
z/8 in. «.. aa «=. o'95 N.A. 610 0 
1/12 in. oil immersion 1°32 N.A. 1210 0 
1/12 in. do a Seo Nae. 16 5 0 
18 BLOOMSBURY SQUARE, W.C. 
for Price 
List of 
“ Gifts.” 
Many of our Scientific Instruments 
are useful, handsome, and acceptable 
GIFTS. 
Recording Barometers from £4 4s. to £27 10s. 
NEGRETTI &@ ZAMBRA, 
38 Holborn Viaduct, London, E.C. 
City Branch: 45 Cornhill, a oe 
West End: 122 Regent St, 
