INVEEKLY ILLUSDRALED! JOURNAL OF SCIENCE, 
“© To the solid g 
Of Nature trusts the mind which builds for aye.” 
round 
—WORDSWORTH. 
‘No. 1423, VOL. 55] 
THURSDAY, FEBRUARY 4, 
1897. [PRICE SIXPENCE. 
[—= 
Registered asa Newspaper at the General Post Office.] 
[All Rights are Reserved. 
NEWTONIAN X-RAY CURRENT METER. 
The principal difficulty in | 
X-Ray photography has | 
been to judge the length of | 
exposure. This can easily be 
done by using an X-Ray | 
Current Meter. Thearrange- | 
ment answers the purpose | 
admirably. The same con- 
ditions can, if desired, be re- | 
produced from day to day, | 
and the voltage being con- | 
stant, the number of amperes, | 
on which the rapidity of ex- 
posure then entirely depends, | 
can be varied as desired and 
adjusted to the greatest 
nicety by the tension screw | 
of the coil. 
“Xx” Ray Current Meter, comprising Ammeter and Volt- 
meter suitable for use with Induction Coils, £5 5s. 
SoLE MAKers: 
NEWwTronw s& CO. 
5, FLERE ET, L ONDON. 
List of Apps-Newton Induction Coils and X-Ray Apparatus Post Free 
on application. 
X-RAY COMPLETE SETS. 
Ser A. Including 3-inch Coil, our own make, Batteries, Focus 
ube, Tube 
7in. X 5 in. . £13 0 0 
Ser 7. Taiciaive 6-inch Coil, Batteries, “Larg rer r Focus Tube, 
Tube Holder, Barium-Platino- Cyanide Screen, 9} in. x 7in. £23 10 0 
BARIUM-PLATINO-CYANIDE SCREENS. 
EXCELLENT FLUORESCENCE, in neat Frames with Handles. 
Holder, Barium-Platino- ce anide Screen, 
7 in. X'5 in., 2ts.; of in. X 7 in., 325. 6d. ; 11} in. X g}in., 555. 
JOHN J. GRIFFIN & SONS, LE: 
(22 GARRICK STREET, LONDON, W.-C. 
NALDER BROS. & CO. 
LONDON. 
N. C. S. 
TELOMSon 
REFLECTING 
GALVANOMETER. 
5000 OHMS RESISTANCE. 
VERY SENSITIVE. 
PRICE 
LS 10 O 
Write for CATALOGUES. 
Cable Address: 
SECOHM, LONDON. 
No Agents in U.S.A. 
This instrument delivered Free anywhere in U.S.A. 
for $60 C.0.D. 
pene & ZAMBRA’S THERMOMETERS. 
The outside Window Bracket Thermometer 
enables the observer to read the Present 
Temperature from inside the House. 
PRICE 2lI/- and upwards, 
Accurate Thermometers for all Purposes. 
ILLUSTRATED PRICE LISTS FREE TO ALL PARTS OF THE WORLD- 
NEGRETTI & -ZAMBRA, 
Scientific Instrument Makers to Her Majesty the 
Queen and British and Foreign Governments, 
38 HOLBORN VIADUCT. 
BRANCHES— 
45 Cornhill, and 122 Regent Street, London. 
Photographic Studios : Crystal Palace. 
