552 
Prof. J. Henry’s Contributions 
of considerable energy, gave some indication that similar 
effects might be produced by a discharge of ordinary elec- 
tricity, provided a sufficiently perfect insulation could be ob- 
tained, 
100. To test this, a hollow glass cylinder, fig. 11, of about 
six inches in diameter, was prepared with a narrow riband of 
Fig. 11. 
tinfoil, about thirty feet long, pasted spirally around the out- 
side, and a similar riband of the same length, pasted on the 
inside ; so that the corresponding spires of the two were di- 
rectly opposite each other. The ends of the inner spiral 
passed out of the cylinder through a glass tube, to prevent 
all direct communication between the two. When the ends 
of the inner riband were joined by the magnetizing spiral 
(11.), containing a needle, and a discharge from a half-gallon 
jar sent through the outer riband, the needle was strongly 
magnetized in such a manner as to indicate an induced current 
through the inner riband in the same direction as that of the 
current of the jar. This experiment was repeated many times, 
and always with the same result. 
101. When the ends of one of the ribands were placed 
very nearly in contact, a small spark was perceived at the 
opening, the moment the discharge took place through the 
other riband. 
102. When the ends of the same riband were separated 
to a considerable distance, a larger spark than the last could 
be drawn from each end by presenting a ball, or the knuckle. 
103. Also if the ends of the outer riband were united, so 
as to form a perfect metallic circuit, a spark could be drawn 
from any point of the same, when a discharge was sent 
through the inner riband. 
104?. The sparks in the two last experiments are evidently 
due to the action known in ordinary electricity by the name 
of the lateral discharge. To render this clear, it is perhaps 
