illustrated and described in a pamphlet accompanying the exhibit. The
perspective illustrations show the machine very clearly, and the
section explains the construction still further. The apparatus
consists of an exterior ring made of iron, about 14 in. in diameter
and 1.5 in wide. It is divided into six equal sections by six small
blocks which project from the inner face of the ring, and which act as
so many magnetic poles. On each of the sections between the blocks is
rolled a coil, of one thickness only, of copper wire about 0.04 in. in
diameter, inclosed in an insulating casing of gutta percha, giving to
the conductor thus protected a total thickness of 0.20 in.; this wire
is coiled, as shown in the illustration. It forms twenty-nine turns in
each section, and the direction of winding changes at each passage in
front of a pole piece. The ends of the wire coinciding with the
horizontal diameter of the ring are stripped of the gutta percha, and
are connected to copper wires which are twisted together and around
two copper rods, which are placed vertically, their lower ends
entering two small cavities made in the base of the apparatus. The
circuit is thus continuous with two ends at opposite points of the
same diameter. The ring is about 1.1 in. thick, and is fixed, as
shown, to two wooden columns, B B, by two blocks of copper, a.

[Illustration: THE ELIAS ELECTROMOTOR.--MADE IN 1842.]

It will be seen from the mode of coiling the wire on this ring, that
if a battery be connected by means of the copper rods, the current
will create six consecutive poles on the various projecting blocks.
The inner ring, E, is about 11 in. in outside diameter, and is also
provided with a series of six projecting pieces which pass before
those on the exterior ring with very little clearance. Between these
projections the space between the inner face of the outer, and the