120 WRITINGS OF JOSEPH HENRY. [1838 



moved from the centre to the inner circumference, as at c ; 

 but when it was placed without the ring, in contact with 

 the outer circumference, at 6, the shocks were very slight ; 

 and when placed within, but its axis at right angles to that 

 of the ring, not the least effect could be observed. 



47. With a little reflection, it will be evident that this 

 arrangement is not the most favorable for exhibiting the 

 induction at a distance, since the side of the ring, for ex- 

 ample, at c, tends to produce a current revolving in one 

 direction in the near side of the helix, and another in an 

 opposite direction in the farther side. The resulting effect 

 is therefore only the difference of the two, and in the position 

 as shown in the figure; this difference must be very small, 

 since the opposite sides of the helix are approximately at the 

 same distance from c. But the difference of action on the 

 two sides constantly increases as the helix is brought near 

 the side of the ring, and becomes a maximum when the two 

 are in the position of internal contact. A helix of larger 

 diameter would therefore produce a greater efl'ect. 



48. Coil No. 1 remaining as before, helix No. 1, which is 

 nine inches in diameter, was substituted for the small helix 

 of the last experiment, and with this the effect at a distance 

 was much increased. When coil No. 2 was added to coil 

 No. 1, and the currents from two small batteries sent through 

 these, shocks were distinctly perceptible through the tongue, 

 when the distance of the planes of the coils and the three 

 helices, united as one, was increased to thirty-six inches. 



49. The action at a distance was still further increased by 

 coiling the long wire of the large spool into the form of a 

 ring of four feet in diameter, and placing parallel to this 

 another ring, formed of the four ribbons of coils No. 1, 2, 3, 

 and 4. When a current from a single battery of thirty-five 

 feet of zinc surface was passed through the ribbon conductor, 

 shocks through the tongue were felt when the rings were 

 separated to the distance of four feet. As the conductors 

 were approximated, the shocks became more and more severe; 

 and when at the distance of twelve inches, they could not be 

 taken through the body. 



