render it available in the construction of new electrical machines. The
following are some of the results obtained in pursuance of this view.

141. The hollow helix already described (6.) was connected with a
galvanometer by wires eight feet long; and the soft iron cylinder (34.)
after being heated red-hot and slowly cooled, to remove all traces of
magnetism, was put into the helix so as to project equally at both ends,
and fixed there. The combined helix and bar were held in the magnetic
direction or line of dip, and (the galvanometer needle being motionless)
were then inverted, so that the lower end should become the upper, but the
whole still correspond to the magnetic direction; the needle was
immediately deflected. As the latter returned to its first position, the
helix and bar were again inverted; and by doing this two or three times,
making the inversions and vibrations to coincide, the needle swung through
an arc of 150° or 160°.

142. When one end of the helix, which may be called A, was uppermost at
first (B end consequently being below), then it mattered not in which
direction it proceeded during the inversion, whether to the right hand or
left hand, or through any other course; still the galvanometer needle
passed in the same direction. Again, when B end was uppermost, the
inversion of the helix and bar in any direction always caused the needle to
be deflected one way; that way being the opposite to the course of the
deflection in the former case.

143. When the helix with its iron core in any given position was inverted,
the effect was as if a magnet with its marked pole downwards had been
introduced from above into the inverted helix. Thus, if the end B were
upwards, such a magnet introduced from above would make the marked end of
the galvanometer needle pass west. Or the end B being downwards, and the