concludes his most interesting communication by describing experiments
made with it in order to convert it into a magneto-electric machine.
"I brought," he says, "near to the coiled armature the opposite poles
of two permanent magnets, and I also excited by the current from a
battery the fixed electro-magnets (see Figs. 3 and 4), and by
mechanical means I rotated the annular armature on its axis. By both
methods I obtained an induced electric current, which was continuous
and always in the same direction, and which, as was indicated by a
galvanometer, proved to be of considerable intensity, although it had
traversed the sulphate of copper voltameter which was included in the
circuit."

Dr. Pacinotti goes on to show that there would be an obvious advantage
in constructing electric generating machines upon this principle, for
by such a system electric currents can be produced which are
continuous and in one direction without the necessity of the
inconvenient and more or less inefficient mechanical arrangements for
commutating the currents and sorting them, so as to collect and
combine those in one direction, separating them from those which are
in the opposite; and he also points our the reversibility of the
apparatus, showing that as an electro-magnetic engine it is capable of
converting a current of electricity into mechanical motion capable of
performing work, while as a magneto-electric machine it is made to
transform mechanical energy into an electric current, which in other
apparatus, forming part of its external circuit, is capable of
performing electric, chemical, or mechanical work.

All these statements are matters of everyday familiarity at the
present day, but it must be remembered that they are records of
experiments made twenty years ago, and as such they entitle their