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 the coils or circuits are coincident.  In cylindrical coils in which the current is uniformly distributed through all the parts of the conductor section, what I here term the electrical middle, or the center of gravity of the ampere turns of the coils, will be the plane at right angles to its axis at its middle, that of B and C, in Fig. 4, being indicated by a dotted line.  To repeat, then, when the centers or center planes of the conductors, Fig. 4, coincide, no indication of electro-inductive repulsion is given, because it is mutually balanced in all directions; but when the coils are displaced, a repulsion is manifested, which reaches a maximum at a position depending on the peculiarities of proportion and distribution of current at any time in the two circuits or conductors.

[Illustration:  FIG. 9.]

It is not my purpose now to discuss the ways of determining the distribution of currents and mechanical effects, as that would extend the present paper much beyond its intended limit.  The forms and relative arrangement of the two conductors may be greatly varied.  In Fig. 5 the parts are of equal diameter, one, B, being a closed ring, and the other, C, being an annular coil placed parallel thereto; and an iron core or wire bundle placed in the common axis of the two coils increases the repulsive action.  B may be simply a disk or plate of any form, without greatly affecting the nature of the action produced.  It may also be composed of a pile of copper washers or a coil of wire, as before indicated.

[Illustration:  FIG. 10.]

An arrangement of parts somewhat analogous to that of a horseshoe electro magnet and armature is shown in Fig. 6.  The alternating current coils, C C’, are wound upon an iron wire bundle bent into U form, and opposite its poles is placed a pair of thick copper disks, B B’, which are attracted and repelled, but with an excess of repulsion depending on their form, thickness, etc.