A WEEKLY IRLUSDRADED JOURNAL. OF SCIENCE: 
“To the solid ground 
Of Nature trusts the mind which builds for aye.” —WORDSWORTH. 
No. 1418, VOL. 55] 
THURSDAY, DECEMBER 31, 1896. 
[PRICE SIXPENCE 
Registered as a 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 
This can easily be 
an ammeter 
exposure. 
done by fusing 
and voltmeter permanently 
in the circuit. The arrange- 
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. 
“*X* Ray Current Meter, comprising Ammeter and Volt- 
meter suitable for use with Induction Coils, £5 5s. 
Sore MAKERS: 
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3 FLEET STREET,.LONDON. 
The rena Gamera 
etecesesooosoveres 
PARTICULARS of this 
unigue HAND-CAMERA 
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Ltd., 
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UP-T°-DATS 
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R. & J. BECK, . 
BROWNINGS SPECTROSCOPES. 
bic = 
THE MINIATURE SPECTROSCOPE. 
This instrument will show many of Fraunhofer’s lines, the 
bright lines of the metals and gases, and the absorption bands in 
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Price, with Plain Slit, 41 2s. ; ditto, with Adjustable Slit in 
Morocco Case, £1 145.; ditto, with Achromatic Lens, &c., 
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Illustrated Catalogue of Spectroscopes, Post Free. 
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63--ST-RAN.D, LONDON, W.-C. 
NEW YEAR'S 
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THE 
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apable of producing Animated Pictures of the highest 
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Price, including Lantern, Oxyhydrogen Burner Limes, &c., complete, £36. 
Films for same, £4 10s. each. 
NEGRETTI & ZAMBRA, 
38 HOLBORN VIADUCT, E.C. : 
Brarche:-—45 CORNHILL, and 122 REGENT STREET. 
YY 
