254 
Prof, J. Henry’s Contributions 
in the weight of the ash after fermentation, although I do not 
imagine it would have been to the extent of fifteen to nine- 
teen times the weight of the ash previous to it. 
Duke Street, Liverpool, March 1840. 
XL VI. Contributions to Electricity and Magnetism, No. IIL 
on Electro-magnetic Induction. Joseph Henry, LL . D.^i 
Prof, of Natural Philosophy in the College of New Jersey^ 
Princeton. 
[Continued from p. 210.] 
Section 0?^ the Induction of Secondary Currents at a 
distance. 
45. TN the experimeirts given in the two preceding sections, 
the conductor which received the induction, was se- 
parated from that which transmitted the primary current by 
the thickness only of a pane of glass ; but the action from this 
arrangement was so energetic, that I was naturally led to try 
the effect at a greater distance. 
46. For this purpose coil No. 1 was formed into a ring of 
Fig. 4. 
a represents helix No. 4, b coil No. 1, in the form of a ring.-, 
about two feet in diameter, and helix No. 4 placed as is shown 
in the figure. When the helix was at the distance of about 
sixteen inches from the middle of the plane of the ring, shocks 
could be perceived through the tongue, and these rapidly in- 
creased in intensity as the helix was lowered, and when it 
reached the plane of the ring they were quite severe. The 
effect, however, was still greater when the helix was moved 
from the centre to the inner circumference, as at but when 
it was placed without the ring, in contact with the outer cir- 
