AY WEEKLY 
ILLUSTRATED JOURNAL OF: SCIENCE/; 
‘To the solid ground 
Of Nature trusts the mind which builds for aye. 
"_ WORDSWORTH. 
No. 2224, VoL. 80] 
_ Registered BS | a Newspaper a at fie Gaiain Post ‘Post Office.) ] 
OPTICAL CONVENTION, 
Science Museum, S. Kensington, June 19-26, 
For the most up-to-date Optical 
Lanterns and Apparatus, Tele- 
scopes, Field Glasses, Sundials, 
and other Scientific Instruments 
of British manufacture, see our 
Exhibit at the above Convention. 
NEWTON & Co., 
By Royal Warrant to H.M. the King, 
72 WIGMORE STREET, W. 
STUDY 
It is the Key to Success in Photography. 
Who can expect to excel who does not understand 
how to use the diaphragm, the swing back, the 
rising front, focussing scale, &c., &e.? All such 
questions are lucidly and simply explained in 
“PHOTOGRAPHIC LENSES : 
A SIMPLE TREATISE.” 
350 pages, 44 plates, 
illustrations, 
numerous diagrams and 
cloth bound. 
R. dep GCK, Ltd fo. SOBs ace, 
__ THURSDAY, _JUNE ioe 1912 
| 
[PRICE SIXPENCE _ 
_ {All Rights ‘Reserved. 
REYNOLDS & BRANSON, Ltd., 
Manufacturers of Chemical Ae 
Physical Apparatus. 
GRAND PRIX AWARD, TURIN, 1911. 
— ” ELECTROSCOPE. 
This 
insulator, remains charged for at least 
Electroscope, with paraffin 
a day, and has been used with the 
greatest satisfaction in many secondary 
schools for the A 
customer states that the batch of two 
last ten years. 
dozen, obtained two years previously, 
has in efficient condition 
during that time. 
remained 
(a) Price with attachment for two Wires and top re-) S/- each. 
movable for cleaning the glasses .. 
(6) Ditto, with two glass tubes for showing the leak- \ 5/6 each. 
age caused by a radio-active gas. 
(ec) Ditto, with transparent scale, lecturer's pattern, 1 
for projection of image of Bole leaf and scale 
by means of a lantern.. : F i 
14 COMMERCIAL STREET, LEEDS. 
7/6 each. 
The finest quality and latest 
improvements are enibodred 
THE LENS | NEGRETTI & ZAMBRA’S 
Equatorial 
f Telescopes. 
New Illustrated Price List 
will be sent post free to 
any part of the world. 
NEGRETTI 
& ZAMBRA, 
Holborn Viaduct, 
London, E.C. 
Branches: 
45 Cornhill, E.C. 
\ ‘ 122 Regent St., W. } 
