AMERICAN 
JOURNAL OF SCIENCE AND ARTS. 
[SECOND SERIES.] 
Art. XV. —On the nature and duration of the dincharge one a 
Leyden jar connected with an induction coil; by O 
Roop, Professor of Physics in Columbia College. -: Pies 
[Read before the National Academy of Sciences, August, 1867.] a 
5. 
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Part Ist. 
; WHEN the terminal wires of an induction coil of cent 
ee ee 
ward in the coil itself. The brightne f the li cht, seg ee 
the ease with which it is generated, render it the most conven- 
ient means in our possession for the production of a nearly in- — 
Stantaneous illumination, while its richness in the violet and 
cence and phosphorescence. Before, however, it can become 
useful for thess and other delicate investigations, involving the 
appreciation of minute intervals of time, it is of course neces- 
ry that the nature and duration of the discharge itself rm 
age tudied, a matter which, so far as I know, has thus far n 
received attention. 
The case of a jar charged by an ordinary frictional machine 
is quite different from the above: here, during the the act of 
charging and feria the two metallic coatings of the jar 
are entirely insulated, while when the induction coil is used in 
Am. Jour. Sc1.—Ssconp Serres, Vou. XLVIII, No; 143.—Szrt., 
il 
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