292 E. W. Blake, Jr., on a method of producing 
the discharge be of negative electricity, and be continued for 
a short time, (e. g. during a quarter-revolution of a 20-inch 
plate of the ordinary frictional machine,) the first effect of de- 
veloping is to bring out a star, which might readily be mistaken 
for the positive figure. Inspection shows however that the 
rays are not depressed, but elevated. e rays are generally 
more or less curved, and resemble the projection on a plane 
of the meridians of a hemisphere. The plane of projection 1s 
different in almost every figure. Precisely such a star occurs 
in the figure, given below, of the negative spark from the in- 
duction coil. 
If the discharge from the point be continued for some seconds, 
the plate, on developing, abe an infinity of minute circular 
Figures produced by the Induction Coil. 
The coil used in these experiments was made at Ruhmkorft’s 
establishment in Paris. It is capable of giving an 8-inch spark, 
but, by reducing the primary current, the striking dis 
was brought down to $ inch. A single Bunsen’s cell was 
fer carbon being withdrawn so as barely to touch the 
nitric aci 
Ne press spark from term- 
inal irene the induc 
tion coil. 
Positive spark from terminal wires of the | 
induction coil. 
__ The positive figure obtained is represented in the accompany” 
ing cut (6). Except its larger size, as compared with frictional 
hicia x. e striking distance, there is nothing notice 
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