conductors apart in an axial line. The part, B, may be replaced by
concentric tubes slid one in the other, or by a pile of flat rings, or
by a closed coil of coarse or fine wire insulated, or not. If the coil,
C, or primary coil, is provided with an iron core such as a bundle of
fine iron wires, the effects are greatly increased in intensity, and the
repulsion with a strong primary current may become quite vigorous, many
pounds of thrust being producible by apparatus of quite moderate size.

The forms and relations of the two parts, C and B, may be greatly
modified, with the general result of a preponderance of repulsive action
when the alternating currents circulate.

Fig. 3 shows the part, B, of an internally tapered or coned form, and C
of an externally coned form, wound on an iron wire bundle, I. The action
in Fig. 2 may be said to be analogous to that of a plain solenoid with
its core, except that repulsion, and not attraction, is produced, while
that of Fig. 3 is more like the action of tapered or conically wound
solenoids and taper cores. Of course, it is unnecessary that both be
tapered. The effect of such shaping is simply to modify the range of
action and the amount of repulsive effort existing at different parts of
the range.

[Illustration: FIG. 8.]

In Fig. 4 the arrangement is modified so that the coil, C, is outside,
and the closed band or circuit, B, inside and around the core, I.
Electro-inductive repulsion is produced as before.

It will be evident that the repulsive actions will not be mechanically
manifested by axial movement or effort when the electrical middles of