554* Prof. J. Henry’s Contributions 
1 08. Experiments were next made in reference to the pro- 
duction of currents of the different orders by ordinary elec- 
tricity. For this purpose a second cylinder was prepared 
with ribands of tinfoil, in a similar manner to the one before 
described. The two were then so connected that the secondary 
current from the first would circulate around the second. 
When a discharge was passed through the outer riband of 
the first cylinder, a tertiary current was induced in the inner 
riband of the second. This was rendered manifest by the 
magnetizing of a needle in a spiral joining the ends of the 
last-mentioned riband. 
109. Also by the addition, in the same w’ay, of a third cy- 
linder, a current of the fourth order was developed. The 
same result was likewise obtained by using the arrangement 
of the coils and helices shown in fig. 9. For these experi- 
ments, however, the coils were furnished with a double coat- 
ing of silk, and the contiguous conductors separated by a 
large plate of glass. 
110. Screening effects precisely the same as those exhibited 
in the action of galvanism were produced by interposing a 
plate of metal between the conductors of different orders, 
figures 8 and 9. The precaution was taken to place the plate 
between two frames of glass, in order to be assured that the 
effect was not due to a want of perfect insulation. 
111. Also analogous results were found when the experi- 
ments were made with coils interposed instead of plates, as 
described in paragraph 68. When the ends of the inter- 
posed coils were separated, no screening was observed ; but 
when joined, the effect was produced. The existence of the 
induced current, in all these experiments, was determined by 
the magnetism of a needle in a spiral attached to one of the 
coils. 
112. Likewise shocks were obtained from the secondary 
current by an arrangement shown in fig. 12. Helices No. 2 
and No. 3 united are put within a glass jar, and coil No. 2 is 
placed around the same. When the handles are grasped, a 
shock is felt at the moment of the discharge, through the outer 
coil. The shocks, however, were very different in intensity 
with different discharges from the jar. In some cases no 
shock was received, when again, with a less charge, a severe 
one was obtained. But these irregularities find an explana- 
tion in a subsequent part of the investigation. 
113. In all these experiments, the results with ordinary 
and galvanic electricity are similar. But at this stage of the 
investigation there appeared what at first was considered a 
remarkable difference in the action of the two. I allude to 
