of
still more recent times. To this group belong the names of Pixii and
Saxton, Holmes and Nollet, Wilde, Varley, Siemens, Wheatstone, and
Pacinotti, who was the first to discover a means of constructing a
machine capable of giving a continuous current always in the same
direction, and which has since proved itself to be the type of nearly
all the direct current electric machines of the present day, and
especially those such as the Gramme and Brush and De Meritens
machines, in which the rotating armature is of annular form; and when
it is considered what a large number of the well known electric
generators are founded upon this discovery, it must be a matter of
general gratification that the recent International Jury of the Paris
Exhibition of Electricity awarded to Dr. Antonio Pacinotti one of
their highest awards.

The original machine designed by Dr. Pacinotti in the year 1860, and
which we illustrate on the present page, formed one of the most
interesting exhibits in the Paris Exhibition, and conferred upon the
Italian Section a very distinctive feature, and we cannot but think
that while all were interested in examining it, there must have been
many who could not help being impressed with the fact that it took
something away from the originality of design in several of the
machines exhibited in various parts of the building.

This very interesting machine was first illustrated and described by
its inventor in the _Nuovo Cimento_ in the year 1864, under the title
"A Description of a Small Electro-Magnetic Machine," and to this
description we are indebted for the information and diagrams contained
in this notice, but the perspective view is taken from the instrument
itself in the Paris Exhibition.

In this very interesting historical communication the author commences
by describing a new form of electro-magnet, consisting of an iron ring
around which is wound (as in the Gramme machine) a single helix of
insulated copper wire completely covering the ring, and the two ends
of the annular helix being soldered together, an annular magnet is
produced, enveloped in an insulated helix forming a closed circuit,
the convolutions of which are all in the same direction. If in such a
system any two points of the coil situated at opposite ends of the
same diameter of the ring be connected respectively with the two poles
of a voltaic battery, the electric current having two courses open to
it, will divide into two portions tr