137 
Mev LY ILSUStTRALED JOURNALMOF SCIENCE. 
“To the solid ground 
Of Nature trusts the mind which builds for aye.”—Worpswortu 
ad 
No. 1431, VOL. 55] THURSDAYS APRIL 1, 1897 [PRICE SIXPENCE. 
Registered as 2 Newspaper at the General Post Office.] {All Rights are Reserved 
INDUCTION COILS. | NALDER BROS. & CO. 
PPS’ PATENTED HERIUTION EDLs are now manufactured 16 RE 
concurrently by D LION ST 
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— i — —— = = ‘ A 
i 
=i 3 
Ai t { 8X 
|THE N.C.S. PATTERN OF THE TROTTER BAR PHOTOMETER. 
This was the Instrument selected by the General Post Office for their 
| tests on Incandescent Lamps. (See Electvician, October 2, 1896, p. 738-) 
Much easier to read than either the shadow or grease-spot instrument. 
Complete with Scale mounted on Bar, and roo Volt Standardised Lamp. 
“X" RAY “FOCUS” TUBES, 25s. 
FLUORESCENT SCREENS, 63s. and 90s. 
tomplete Apparatus for R6ntgen “X” Rays, with Coils Price £9. 
iu aot ec base nee: | ne s OR CaTALoGuE. Cable Address, “' Secoum, Lonpon.” 
Dam Application. iar Coe ae ee er aaa 
HEAT INDICATING SCREENS. pee ee ND THERMOGRAPT 
ik | R ND_THERMOGRAPHS. 
The Double JODIDE for preparing the above, mall ; 
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NVALUABLE TO LECTURERS AND SCIENCE | 
: DEMONSTRATORS. 
WRITE FOR PARTICULARS AND INSTRUCTIONS, and aaanaile = 
also for CATALOGUE of aaeaatil | a 
X-RAY APPARATUS, a fae 
INCLUDING 
NDUCTION COILS, TESLA COILS, Sa 
TU BES, SCREEN S, BATTERIES, The Barograph is fitted in a Mahogany Case with Glass Front, as shown 
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&c., Ke. on Charts, which only require changing once a week, and are invaluable to 
— invalids and others who are unable to take daily readings of the ordinary 
\LL KINDS OF PHYSICAL AND CHEMICAL | instruments. Price of each, with supply of Charts for one year, £6 10s. 
APPARATUS manufactured by NEGRETTI & ZAMBRA, 
SCIENTIFIC INSTRUMENT MAKERS to the QUEEN, 
JOHN J. GRIFFIN & SONS, E 38 HOLBORN VIADUCT, E.C. 
12 GARRICK STREET, LONDON, W.C. Branches : 45 CORNHILL, and 122 REGENT STREET. 
’ 
