and dates back to July, 1871, an epoch at which appeared a memoir
(entitled "Note upon a magneto-electric machine that produces
continuous currents") that was read to the Academy of Sciences by Mr.
Jamin. Ten years previous, Pacinotti had had a glimpse of the
phenomenon, and of its practical realization, but was unfortunately
unable to appreciate the importance of his discovery and the benefit
that might be reaped from it. It is of slight consequence whether
Gramme knew of this experiment or not, for the glory that attaches to
his name could not be diminished for all that. But an interesting fact
that we propose to dwell upon now has recently been brought to light
in an electrical review published at Vienna.[1] It results from
documents whose authenticity cannot be doubted that, as far back as
1867, Mr. L. Pfaundler, a professor at Innsbruck, very clearly
announced the reversibility of a magneto-electric motor constructed by
Kravogl, a mechanician of the same place, and that he succeeded some
time before Gramme in obtaining continuous currents.

[Footnote 1: _Zeitschrift des Electrotechnischen Vereines_ in
_Wien_, July, 1883.]

The Kravogl motor that figured at the Universal Exhibition of 1867 is
but little known, and it is now very difficult to obtain drawings of
it. What is certain is that this motor is an application of the
properties of the solenoid, and, from this standpoint, resembles the
Bessolo motor that was patented in 1855. We may figure the apparatus
to our mind very well if we suppose that in the Gramme ring a half and
almost two-thirds of the core are removed, and the spirals are movable
around the said core. If a current be sent into a portion of the
spirals only, and in such a way that only half of the core be exposed,
the latter will move with respect to the bobbin or the bobbin with